Fix a new warning for Swift 6.2

* Document everything

* Make sure ReadmeExamples are up to date

Changelog.md

@@ -0,0 +1,77 @@
+# Changelog
+
+## [Unreleased]
+
+- Your change here.
+
+[Unreleased]: https://github.com/samsonjs/AsyncMonitor/compare/0.3.1...HEAD
+
+## [0.3.1] - 2025-05-25
+
+### Changed
+- Updated documentation in Readme.md
+
+[0.3.1]: https://github.com/samsonjs/AsyncMonitor/compare/0.3...0.3.1
+
+## [0.3] - 2025-05-25
+
+### Added
+- Support for iOS 17 and macOS 14 (expanded platform compatibility)
+- Legacy initializers and monitor methods with Sendable requirements for iOS 17+ compatibility
+- Backward compatibility layer for actor isolation features
+
+### Changed
+- Enhanced AsyncMonitor class with dual initializer pattern for different iOS versions
+- Improved AsyncSequence extensions with version-specific monitor methods
+- Updated NSObject+AsyncKVO implementation for broader platform support
+
+[0.3]: https://github.com/samsonjs/AsyncMonitor/compare/0.2.1...0.3
+
+## [0.2.1] - 2025-04-26
+
+### Changed
+- **Breaking**: Refactored KVO monitoring API
+  - Split `values` method into separate `values(for:)` method that returns AsyncStream
+  - Added `monitorValues(for:)` convenience method that combines values observation with monitoring
+- Replaced `TokenLocker` with `ValueLocker` for improved value management
+
+### Added
+- Enhanced test coverage for NSObject+AsyncKVO functionality
+- Additional test cases for async cancellable behavior
+
+[0.2.1]: https://github.com/samsonjs/AsyncMonitor/compare/0.2...0.2.1
+
+## [0.2] - 2025-04-26
+
+### Changed
+- Version bump to 0.2
+
+[0.2]: https://github.com/samsonjs/AsyncMonitor/compare/0.1.1...0.2
+
+## [0.1.1] - 2025-04-25
+
+### Changed
+- Updated minimum iOS platform requirement to 18.0
+- Removed main actor restrictions from public API
+
+### Added
+- Comprehensive documentation comments on public API
+- Enhanced README with detailed usage examples and patterns
+- Expanded test suite coverage
+
+[0.1.1]: https://github.com/samsonjs/AsyncMonitor/compare/0.1...0.1.1
+
+## [0.1] - 2025-04-25
+
+### Added
+- Initial release of AsyncMonitor
+- Core `AsyncMonitor` class for wrapping async sequence observation in manageable Tasks
+- `AsyncCancellable` protocol and `AnyAsyncCancellable` type-eraser for uniform cancellation
+- AsyncSequence extensions with `.monitor()` convenience methods
+- KVO integration via `NSObject+AsyncKVO` extension
+- Support for context-aware monitoring to prevent reference cycles
+- Swift Testing framework integration
+- Comprehensive test suite
+- Documentation and usage examples
+
+[0.1]: https://github.com/samsonjs/AsyncMonitor/releases/tag/0.1

Package.swift

@@ -5,8 +5,8 @@ import PackageDescription
 let package = Package(
     name: "AsyncMonitor",
     platforms: [
-        .iOS(.v18),
+        .iOS(.v17),
-        .macOS(.v15),
+        .macOS(.v14),
     ],
     products: [
         .library(

Readme.md

@@ -10,59 +10,35 @@ AsyncMonitor is a Swift library that provides a simple and easy-to-use way to ma
 
 It uses a Swift `Task` to ensure that all resources are properly cleaned up when the `AsyncMonitor` is cancelled or deallocated.
 
-That's it. It's pretty trivial. I just got tired of writing it over and over, mainly for notifications. You still have to map your `Notification`s to something sendable.
+That's it. It's pretty trivial. I just got tired of writing it over and over, mainly for notifications. You still have to map your `Notification`s to something sendable, which brings me to another point. This package pairs nicely with [NotificationSmuggler](https://github.com/samsonjs/NotificationSmuggler) for a complete notification handling system in the Swift 6 concurrency world.
-
-## Installation
-
-The only way to install this package is with Swift Package Manager (SPM). Please [file a new issue][] or submit a pull-request if you want to use something else.
-
-[file a new issue]: https://github.com/samsonjs/AsyncMonitor/issues/new
-
-### Supported Platforms
-
-This package is supported on iOS 18.0+ and macOS 15.0+.
-
-### Xcode
-
-When you're integrating this into an app with Xcode then go to your project's Package Dependencies and enter the URL `https://github.com/samsonjs/AsyncMonitor` and then go through the usual flow for adding packages.
-
-### Swift Package Manager (SPM)
-
-When you're integrating this using SPM on its own then add this to the list of dependencies your Package.swift file:
-
-```swift
-.package(url: "https://github.com/samsonjs/AsyncMonitor.git", .upToNextMajor(from: "0.1.0"))
-```
-
-and then add `"AsyncMonitor"` to the list of dependencies in your target as well.
 
 ## Usage
 
-The simplest example uses a closure that receives the notification:
+The simplest example uses a closure that receives the notification. The closure is async so you can await in there if you need to.
 
 ```swift
 import AsyncMonitor
 
-@MainActor class SimplestVersion {
+class SimplestVersion {
     let cancellable = NotificationCenter.default
-        .notifications(named: .NSCalendarDayChanged).map(\.name)
+        .notifications(named: .NSCalendarDayChanged)
+        .map(\.name)
         .monitor { _ in
             print("The date is now \(Date.now)")
         }
 }
 ```
 
-This example uses the context parameter to avoid reference cycles with `self`:
+This example uses the context parameter to avoid reference cycles with `self`.
 
 ```swift
-import AsyncMonitor
+final class WithContext: Sendable {
-
+    nonisolated(unsafe) var cancellables = Set<AnyAsyncCancellable>()
-@MainActor class WithContext {
-    var cancellables = Set<AnyAsyncCancellable>()
 
     init() {
         NotificationCenter.default
-            .notifications(named: .NSCalendarDayChanged).map(\.name)
+            .notifications(named: .NSCalendarDayChanged)
+            .map(\.name)
             .monitor(context: self) { _self, _ in
                 _self.dayChanged()
             }.store(in: &cancellables)
@@ -74,7 +50,71 @@ import AsyncMonitor
 }
 ```
 
-The closure is async so you can await in there if you need to.
+### Combine
+
+Working with Combine publishers is trivial thanks to [`AnyPublisher.values`][values].
+
+```swift
+@preconcurrency import Combine
+
+class CombineExample {
+    var cancellables: Set<AnyAsyncCancellable> = []
+
+    init() {
+        Timer.publish(every: 1.0, on: .main, in: .common)
+            .autoconnect()
+            .values
+            .monitor { date in
+                print("Timer fired at \(date)")
+            }.store(in: &cancellables)
+    }
+}
+```
+
+[values]: https://developer.apple.com/documentation/combine/anypublisher/values-3s2uy
+
+### Key-Value Observing (KVO) extension
+
+When you need to observe an object that uses [KVO][] there's an extension method you can use to monitor it:
+
+```swift
+class KVOExample {
+    var cancellables: Set<AnyAsyncCancellable> = []
+
+    init() {
+        let progress = Progress(totalUnitCount: 42)
+        progress.monitorValues(for: \.fractionCompleted, options: [.initial, .new]) { fraction in
+            print("Progress is \(fraction.formatted(.percent))%")
+        }.store(in: &cancellables)
+    }
+}
+```
+
+[KVO]: https://developer.apple.com/library/archive/documentation/General/Conceptual/DevPedia-CocoaCore/KVO.html
+
+## Installation
+
+The only way to install this package is with Swift Package Manager (SPM). Please [file a new issue][] or submit a pull-request if you want to use something else.
+
+[file a new issue]: https://github.com/samsonjs/AsyncMonitor/issues/new
+
+### Supported Platforms
+
+This package is supported on iOS 17.0+ and macOS 14.0+.
+
+### Xcode
+
+When you're integrating this into an app with Xcode then go to your project's Package Dependencies and enter the URL `https://github.com/samsonjs/AsyncMonitor` and then go through the usual flow for adding packages.
+
+### Swift Package Manager (SPM)
+
+When you're integrating this using SPM on its own then add this to the list of dependencies your Package.swift file:
+
+```swift
+.package(url: "https://github.com/samsonjs/AsyncMonitor.git", .upToNextMajor(from: "0.3.1"))
+```
+
+and then add `"AsyncMonitor"` to the list of dependencies in your target as well.
 
 ## License
 

Sources/AsyncMonitor/AnyAsyncCancellable.swift

@@ -1,7 +1,20 @@
+/// Type-erasing wrapper for ``AsyncCancellable`` that automatically cancels when deallocated.
+///
+/// `AnyAsyncCancellable` provides automatic cancellation when deallocated, making it safe to store
+/// cancellables without explicitly managing their lifecycle.
+///
 public class AnyAsyncCancellable: AsyncCancellable {
+    lazy var id = ObjectIdentifier(self)
+
     let canceller: () -> Void
 
-    init<AC: AsyncCancellable>(cancellable: AC) {
+    /// Creates a type-erased wrapper around the provided cancellable.
+    ///
+    /// The wrapper will call the cancellable's `cancel()` method when either
+    /// explicitly cancelled or deallocated.
+    ///
+    /// - Parameter cancellable: The ``AsyncCancellable`` to wrap.
+    public init<AC: AsyncCancellable>(cancellable: AC) {
         canceller = { cancellable.cancel() }
     }
 
@@ -11,6 +24,7 @@ public class AnyAsyncCancellable: AsyncCancellable {
 
     // MARK: AsyncCancellable conformance
 
+    /// Cancels the wrapped cancellable. Safe to call multiple times and automatically called on deallocation.
     public func cancel() {
         canceller()
     }
@@ -18,10 +32,10 @@ public class AnyAsyncCancellable: AsyncCancellable {
     // MARK: Hashable conformance
 
     public static func == (lhs: AnyAsyncCancellable, rhs: AnyAsyncCancellable) -> Bool {
-        ObjectIdentifier(lhs) == ObjectIdentifier(rhs)
+        lhs.id == rhs.id
     }
 
     public func hash(into hasher: inout Hasher) {
-        hasher.combine(ObjectIdentifier(self))
+        hasher.combine(id)
     }
 }

Sources/AsyncMonitor/AsyncCancellable.swift

@@ -1,9 +1,20 @@
-public protocol AsyncCancellable: Hashable {
+/// Represents an async operation that can be cancelled.
+///
+/// `AsyncCancellable` provides a common interface for cancelling async operations, similar to
+/// Combine's `AnyCancellable` but designed for Swift concurrency patterns.
+///
+public protocol AsyncCancellable: AnyObject, Hashable {
+    /// Cancels the operation. Safe to call multiple times.
     func cancel()
 
+    /// Stores this cancellable in the given set using ``AnyAsyncCancellable``.
+    ///
+    /// - Parameter set: The set to store the wrapped cancellable in.
     func store(in set: inout Set<AnyAsyncCancellable>)
 }
 
+// MARK: Default implementations
+
 public extension AsyncCancellable {
     func store(in set: inout Set<AnyAsyncCancellable>) {
         set.insert(AnyAsyncCancellable(cancellable: self))

Sources/AsyncMonitor/AsyncMonitor.docc/AsyncMonitor.md

@@ -0,0 +1,112 @@
+# ``AsyncMonitor``
+
+Wraps async sequence observation in manageable tasks.
+
+## Overview
+
+AsyncMonitor wraps async sequence observation in a `Task` that can be cancelled and stored. It preserves actor isolation on iOS 18+ and includes KVO integration.
+
+## Basic Usage
+
+```swift
+import AsyncMonitor
+
+// Monitor notifications
+NotificationCenter.default
+    .notifications(named: .NSCalendarDayChanged)
+    .map(\.name)
+    .monitor { _ in print("Day changed!") }
+
+// Store for longer lifetime
+var cancellables: Set<AnyAsyncCancellable> = []
+
+sequence.monitor { element in
+    // Handle element
+}.store(in: &cancellables)
+```
+
+## Context-Aware Monitoring
+
+Prevent retain cycles with weak context:
+
+```swift
+class DataController {
+    var cancellables: Set<AnyAsyncCancellable> = []
+    
+    func startMonitoring() {
+        dataStream
+            .monitor(context: self) { controller, data in
+                controller.processData(data)
+            }.store(in: &cancellables)
+    }
+}
+```
+
+## KVO Integration
+
+```swift
+let progress = Progress(totalUnitCount: 100)
+
+progress.monitorValues(for: \.fractionCompleted, options: [.initial, .new]) { fraction in
+    print("Progress: \(fraction.formatted(.percent))")
+}.store(in: &cancellables)
+```
+
+## Error Handling
+
+Both throwing and non-throwing sequences work. Errors are caught and logged automatically.
+
+```swift
+// Non-throwing
+Timer.publish(every: 1.0, on: .main, in: .common)
+    .autoconnect()
+    .values
+    .monitor { date in print("Timer: \(date)") }
+
+// Throwing (errors caught automatically)
+networkDataStream()
+    .monitor { data in processData(data) }
+```
+
+## Memory Management
+
+Use weak captures or context to avoid retain cycles:
+
+```swift
+// Good
+sequence.monitor(context: self) { controller, element in
+    controller.handle(element)
+}
+
+// Good
+sequence.monitor { [weak self] element in
+    self?.handle(element)
+}
+
+// Bad - creates retain cycle
+sequence.monitor { element in
+    self.handle(element)
+}
+```
+
+## Platform Requirements
+
+- iOS 17.0+ / macOS 14.0+
+- Swift 6.0+
+
+## Topics
+
+### Core Types
+
+- ``AsyncMonitor`` - Wraps async sequence observation in a managed Task
+- ``AsyncCancellable`` - Protocol for async operations that can be cancelled
+- ``AnyAsyncCancellable`` - Type-erasing wrapper that auto-cancels on deallocation
+
+### Sequence Extensions
+
+- ``Foundation/AsyncSequence/monitor(_:)``
+- ``Foundation/AsyncSequence/monitor(context:_:)``
+
+### KVO Integration
+
+- ``Foundation/NSObjectProtocol/monitorValues(for:options:changeHandler:)``

Sources/AsyncMonitor/AsyncMonitor.swift

@@ -1,6 +1,27 @@
+/// A monitor that observes an asynchronous sequence and invokes the given block for each received element.
+///
+/// `AsyncMonitor` wraps the observation of an async sequence in a `Task`, providing automatic cancellation
+/// and memory management. Elements must be `Sendable`. For notifications, map to something sendable:
+///
+/// ```swift
+/// NotificationCenter.default
+///     .notifications(named: .NSCalendarDayChanged)
+///     .map(\.name)
+///     .monitor { _ in print("Day changed!") }
+/// ```
+///
+/// On iOS 18+, preserves the caller's actor isolation context by default.
+///
 public final class AsyncMonitor: Hashable, AsyncCancellable {
     let task: Task<Void, Never>
 
+    /// Creates an ``AsyncMonitor`` that observes the provided asynchronous sequence with actor isolation support (iOS 18+).
+    ///
+    /// - Parameters:
+    ///   - isolation: An optional actor isolation context to inherit. Defaults to `#isolation`.
+    ///   - sequence: The asynchronous sequence of elements to observe.
+    ///   - block: A closure to execute for each element yielded by the sequence.
+    @available(iOS 18, macOS 15, *)
     public init<Element: Sendable>(
         isolation: isolated (any Actor)? = #isolation,
         sequence: any AsyncSequence<Element, Never>,
@@ -15,12 +36,62 @@ public final class AsyncMonitor: Hashable, AsyncCancellable {
         }
     }
 
+    /// Creates an ``AsyncMonitor`` for sequences that may throw errors (iOS 18+).
+    ///
+    /// - Parameters:
+    ///   - isolation: An optional actor isolation context to inherit. Defaults to `#isolation`.
+    ///   - sequence: The asynchronous sequence of elements to observe. May throw errors.
+    ///   - block: A closure to execute for each element yielded by the sequence.
+    @available(iOS 18, macOS 15, *)
+    public init<Element: Sendable, Sequence: AsyncSequence>(
+        isolation: isolated (any Actor)? = #isolation,
+        sequence: Sequence,
+        performing block: @escaping (Element) async -> Void
+    ) where Sequence.Element == Element {
+        self.task = Task {
+            _ = isolation // use capture trick to inherit isolation
+
+            do {
+                for try await element in sequence {
+                    await block(element)
+                }
+            } catch {
+                guard !Task.isCancelled else { return }
+            }
+        }
+    }
+
+    /// Creates an ``AsyncMonitor`` for iOS 17 compatibility.
+    ///
+    /// - Parameters:
+    ///   - sequence: The asynchronous sequence of elements to observe. Must be `Sendable`.
+    ///   - block: A `@Sendable` closure to execute for each element yielded by the sequence.
+    @available(iOS, introduced: 17, obsoleted: 18)
+    @available(macOS, introduced: 14, obsoleted: 15)
+    public init<Element: Sendable, Sequence>(
+        sequence: sending Sequence,
+        @_inheritActorContext performing block: @escaping @Sendable (Element) async -> Void
+    ) where Sequence: AsyncSequence & Sendable, Sequence.Element == Element {
+        self.task = Task {
+            do {
+                for try await element in sequence {
+                    await block(element)
+                }
+            } catch {
+                guard !Task.isCancelled else { return }
+
+                print("Error iterating over sequence: \(error)")
+            }
+        }
+    }
+
     deinit {
         cancel()
     }
 
     // MARK: AsyncCancellable conformance
 
+    /// Cancels the underlying task. Safe to call multiple times and automatically called when deallocated.
     public func cancel() {
         task.cancel()
     }

Sources/AsyncMonitor/AsyncSequence+Extensions.swift

@@ -1,4 +1,36 @@
+@available(iOS 18, macOS 15, *)
 public extension AsyncSequence where Element: Sendable, Failure == Never {
+    /// Observes the elements yielded by this sequence and executes the given closure with each element.
+    ///
+    /// This method creates an ``AsyncMonitor`` that observes the sequence and preserves the caller's
+    /// actor isolation context by default. When called from a `@MainActor` context, the monitoring
+    /// block will also run on the main actor.
+    ///
+    /// - Parameters:
+    ///   - isolation: An optional actor isolation context to inherit. Defaults to `#isolation`, 
+    ///                preserving the caller's actor isolation.
+    ///   - block: A closure that's executed with each yielded element. The closure runs with
+    ///            the same actor isolation as the caller.
+    ///
+    /// - Returns: An ``AsyncMonitor`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// @MainActor class ViewModel {
+    ///     var cancellables: Set<AnyAsyncCancellable> = []
+    ///     
+    ///     func startMonitoring() {
+    ///         // Monitor runs on MainActor since caller is @MainActor
+    ///         NotificationCenter.default
+    ///             .notifications(named: .NSCalendarDayChanged)
+    ///             .map(\.name)
+    ///             .monitor { _ in
+    ///                 self.updateUI() // Safe to call @MainActor methods
+    ///             }.store(in: &cancellables)
+    ///     }
+    /// }
+    /// ```
     func monitor(
         isolation: isolated (any Actor)? = #isolation,
         _ block: @escaping (Element) async -> Void
@@ -6,6 +38,40 @@ public extension AsyncSequence where Element: Sendable, Failure == Never {
         AsyncMonitor(isolation: isolation, sequence: self, performing: block)
     }
 
+    /// Observes the elements yielded by this sequence and executes the given closure with each element and the weakly-captured context object.
+    ///
+    /// This method creates an ``AsyncMonitor`` that weakly captures the provided context object, preventing retain cycles.
+    /// If the context object is deallocated, the monitoring block will not be executed for subsequent elements.
+    ///
+    /// - Parameters:
+    ///   - isolation: An optional actor isolation context to inherit. Defaults to `#isolation`, 
+    ///                preserving the caller's actor isolation.
+    ///   - context: The object to capture weakly for use within the closure. This prevents retain cycles
+    ///              when the context holds a reference to the monitor.
+    ///   - block: A closure that's executed with the weakly-captured context and each yielded element.
+    ///            The closure runs with the same actor isolation as the caller.
+    ///
+    /// - Returns: An ``AsyncMonitor`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// class DataManager {
+    ///     var cancellables: Set<AnyAsyncCancellable> = []
+    ///     
+    ///     func startMonitoring() {
+    ///         // Context is weakly captured, preventing retain cycle
+    ///         dataStream
+    ///             .monitor(context: self) { manager, data in
+    ///                 manager.process(data) // manager won't be nil here
+    ///             }.store(in: &cancellables)
+    ///     }
+    ///     
+    ///     func process(_ data: Data) {
+    ///         // Process the data
+    ///     }
+    /// }
+    /// ```
     func monitor<Context: AnyObject>(
         isolation: isolated (any Actor)? = #isolation,
         context: Context,
@@ -17,3 +83,160 @@ public extension AsyncSequence where Element: Sendable, Failure == Never {
         }
     }
 }
+
+@available(iOS 18, macOS 15, *)
+public extension AsyncSequence where Element: Sendable {
+    /// Observes the elements yielded by this sequence and executes the given closure with each element.
+    ///
+    /// This method creates an ``AsyncMonitor`` that observes the sequence and preserves the caller's
+    /// actor isolation context by default. When called from a `@MainActor` context, the monitoring
+    /// block will also run on the main actor.
+    ///
+    /// This version handles sequences that may throw errors. If an error is thrown, it will be logged
+    /// and monitoring will stop.
+    ///
+    /// - Parameters:
+    ///   - isolation: An optional actor isolation context to inherit. Defaults to `#isolation`, 
+    ///                preserving the caller's actor isolation.
+    ///   - block: A closure that's executed with each yielded element. The closure runs with
+    ///            the same actor isolation as the caller.
+    ///
+    /// - Returns: An ``AsyncMonitor`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// NotificationCenter.default
+    ///     .notifications(named: .NSCalendarDayChanged)
+    ///     .map(\.name)
+    ///     .monitor { _ in
+    ///         print("Day changed!")
+    ///     }.store(in: &cancellables)
+    /// ```
+    func monitor(
+        isolation: isolated (any Actor)? = #isolation,
+        _ block: @escaping (Element) async -> Void
+    ) -> AsyncMonitor {
+        AsyncMonitor(isolation: isolation, sequence: self, performing: block)
+    }
+
+    /// Observes the elements yielded by this sequence and executes the given closure with each element and the weakly-captured context object.
+    ///
+    /// This method creates an ``AsyncMonitor`` that weakly captures the provided context object, preventing retain cycles.
+    /// If the context object is deallocated, the monitoring block will not be executed for subsequent elements.
+    ///
+    /// This version handles sequences that may throw errors. If an error is thrown, it will be logged
+    /// and monitoring will stop.
+    ///
+    /// - Parameters:
+    ///   - isolation: An optional actor isolation context to inherit. Defaults to `#isolation`, 
+    ///                preserving the caller's actor isolation.
+    ///   - context: The object to capture weakly for use within the closure. This prevents retain cycles
+    ///              when the context holds a reference to the monitor.
+    ///   - block: A closure that's executed with the weakly-captured context and each yielded element.
+    ///            The closure runs with the same actor isolation as the caller.
+    ///
+    /// - Returns: An ``AsyncMonitor`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// class DataManager {
+    ///     var cancellables: Set<AnyAsyncCancellable> = []
+    ///     
+    ///     func startMonitoring() {
+    ///         notificationStream
+    ///             .monitor(context: self) { manager, notification in
+    ///                 manager.handleNotification(notification)
+    ///             }.store(in: &cancellables)
+    ///     }
+    /// }
+    /// ```
+    func monitor<Context: AnyObject>(
+        isolation: isolated (any Actor)? = #isolation,
+        context: Context,
+        _ block: @escaping (Context, Element) async -> Void
+    ) -> AsyncMonitor {
+        AsyncMonitor(isolation: isolation, sequence: self) { [weak context] element in
+            guard let context else { return }
+            await block(context, element)
+        }
+    }
+}
+
+@available(iOS, introduced: 17, obsoleted: 18)
+@available(macOS, introduced: 14, obsoleted: 15)
+public extension AsyncSequence where Self: Sendable, Element: Sendable {
+    /// Observes the elements yielded by this sequence and executes the given closure with each element (iOS 17 compatibility).
+    ///
+    /// This method provides backward compatibility for iOS 17. It requires both the sequence and its elements
+    /// to be `Sendable`, and uses a `@Sendable` closure for thread safety.
+    ///
+    /// - Parameters:
+    ///   - block: A `@Sendable` closure that's executed with each yielded element.
+    ///
+    /// - Returns: An ``AsyncMonitor`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// let cancellable = sendableAsyncSequence.monitor { element in
+    ///     print("Received: \(element)")
+    /// }
+    /// 
+    /// // Store for automatic cleanup
+    /// cancellable.store(in: &cancellables)
+    /// ```
+    ///
+    /// - Note: This method is deprecated in iOS 18+ in favour of ``monitor(isolation:_:)``
+    ///   which provides better actor isolation support.
+    func monitor(
+        _ block: @escaping @Sendable (Element) async -> Void
+    ) -> AsyncMonitor {
+        AsyncMonitor(sequence: self, performing: block)
+    }
+
+    /// Observes the elements yielded by this sequence and executes the given closure with each element and the weakly-captured context object (iOS 17 compatibility).
+    ///
+    /// This method provides backward compatibility for iOS 17 with weak reference handling to prevent retain cycles.
+    /// It requires the context to be both `AnyObject` and `Sendable` for thread safety.
+    ///
+    /// - Parameters:
+    ///   - context: The object to capture weakly for use within the closure. Must be `Sendable` and will be
+    ///              captured weakly to prevent retain cycles.
+    ///   - block: A `@Sendable` closure that's executed with the weakly-captured context and each yielded element.
+    ///
+    /// - Returns: An ``AsyncMonitor`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// class SendableDataManager: Sendable {
+    ///     var cancellables: Set<AnyAsyncCancellable> = []
+    ///     
+    ///     func startMonitoring() {
+    ///         // Context is weakly captured, preventing retain cycle
+    ///         sendableDataStream
+    ///             .monitor(context: self) { manager, data in
+    ///                 manager.process(data)
+    ///             }.store(in: &cancellables)
+    ///     }
+    ///     
+    ///     func process(_ data: Data) {
+    ///         // Process the data
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// - Note: This method is deprecated in iOS 18+ in favour of ``monitor(isolation:context:_:)``
+    ///   which provides better actor isolation support.
+    func monitor<Context: AnyObject & Sendable>(
+        context: Context,
+        _ block: @escaping @Sendable (Context, Element) async -> Void
+    ) -> AsyncMonitor {
+        AsyncMonitor(sequence: self) { [weak context] element in
+            guard let context else { return }
+            await block(context, element)
+        }
+    }
+}

Sources/AsyncMonitor/NSObject+AsyncKVO.swift

@@ -3,18 +3,150 @@ public import Foundation
 extension KeyPath: @unchecked @retroactive Sendable where Value: Sendable {}
 
 public extension NSObjectProtocol where Self: NSObject {
+    /// Returns an `AsyncSequence` of values for all changes to the given key path on this object.
+    ///
+    /// This method creates an `AsyncStream` that yields the current value of the specified key path
+    /// whenever it changes via Key-Value Observing (KVO). The stream automatically manages the KVO
+    /// observation lifecycle and cleans up when the stream is terminated.
+    ///
+    /// - Parameters:
+    ///   - keyPath: The key path to observe on this object. The value type must be `Sendable`
+    ///              to ensure thread safety across async contexts.
+    ///   - options: KVO options to use for observation. Defaults to an empty set.
+    ///              See `NSKeyValueObservingOptions` for available options.
+    ///
+    /// - Returns: An `AsyncStream<Value>` that yields the current value of the key path
+    ///            whenever it changes.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// let progress = Progress(totalUnitCount: 100)
+    /// 
+    /// for await fraction in progress.values(for: \.fractionCompleted) {
+    ///     print("Progress: \(fraction.formatted(.percent))")
+    ///     if fraction >= 1.0 { break }
+    /// }
+    /// ```
+    ///
+    /// ## Thread Safety
+    ///
+    /// The returned stream is thread-safe and can be consumed from any actor context.
+    /// The KVO observation token is automatically retained by the stream and released
+    /// when the stream terminates.
+    ///
+    /// - Important: The observed object must remain alive for the duration of the observation.
+    ///   If the object is deallocated, the stream will terminate.
     func values<Value: Sendable>(
         for keyPath: KeyPath<Self, Value>,
-        options: NSKeyValueObservingOptions = [],
+        options: NSKeyValueObservingOptions = []
-        changeHandler: @escaping @MainActor (Value) -> Void
+    ) -> AsyncStream<Value> {
-    ) -> any AsyncCancellable {
         let (stream, continuation) = AsyncStream<Value>.makeStream()
-        let token = self.observe(keyPath, options: options) { object, _ in
+        let token: NSKeyValueObservation? = self.observe(keyPath, options: options) { object, _ in
             continuation.yield(object[keyPath: keyPath])
         }
-        return stream.monitor { @MainActor value in
+        // A nice side-effect of this is that the stream retains the token automatically.
-            _ = token // keep this alive
+        let locker = ValueLocker(value: token)
-            changeHandler(value)
+        continuation.onTermination = { _ in
+            locker.modify { $0 = nil }
         }
+        return stream
+    }
+}
+
+@available(iOS 18, macOS 15, *)
+public extension NSObjectProtocol where Self: NSObject {
+    /// Observes changes to the specified key path on the object and executes a handler for each change.
+    ///
+    /// This method combines KVO observation with ``AsyncMonitor`` to provide a convenient way to
+    /// monitor object property changes. It creates an ``AsyncMonitor`` that observes the key path
+    /// and preserves the caller's actor isolation context.
+    ///
+    /// - Parameters:
+    ///   - keyPath: The key path to observe on this object. The value type must be `Sendable`
+    ///              to ensure thread safety across async contexts.
+    ///   - options: KVO options to use for observation. Defaults to an empty set.
+    ///              See `NSKeyValueObservingOptions` for available options.
+    ///   - changeHandler: A closure that's executed with each new value. The closure runs with
+    ///                    the same actor isolation as the caller.
+    ///
+    /// - Returns: An ``AsyncCancellable`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// @MainActor class ProgressView: UIView {
+    ///     var cancellables: Set<AnyAsyncCancellable> = []
+    ///     
+    ///     func observeProgress(_ progress: Progress) {
+    ///         // Handler runs on MainActor since caller is @MainActor
+    ///         progress.monitorValues(for: \.fractionCompleted) { [weak self] fraction in
+    ///             self?.updateProgressBar(fraction)
+    ///         }.store(in: &cancellables)
+    ///     }
+    ///     
+    ///     func updateProgressBar(_ fraction: Double) {
+    ///         // Update UI safely on MainActor
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// ## Usage with KVO Options
+    ///
+    /// ```swift
+    /// object.monitorValues(for: \.property, options: [.initial, .new]) { newValue in
+    ///     print("Property changed to: \(newValue)")
+    /// }
+    /// ```
+    func monitorValues<Value: Sendable>(
+        for keyPath: KeyPath<Self, Value>,
+        options: NSKeyValueObservingOptions = [],
+        changeHandler: @escaping (Value) -> Void
+    ) -> any AsyncCancellable {
+        values(for: keyPath, options: options)
+            .monitor(changeHandler)
+    }
+}
+
+@available(iOS, introduced: 17, obsoleted: 18)
+@available(macOS, introduced: 14, obsoleted: 15)
+public extension NSObjectProtocol where Self: NSObject {
+    /// Observes changes to the specified key path on the object and executes a handler for each change (iOS 17 compatibility).
+    ///
+    /// This method provides backward compatibility for iOS 17. It combines KVO observation with ``AsyncMonitor``
+    /// and requires a `@Sendable` closure for thread safety.
+    ///
+    /// - Parameters:
+    ///   - keyPath: The key path to observe on this object. The value type must be `Sendable`
+    ///              to ensure thread safety across async contexts.
+    ///   - options: KVO options to use for observation. Defaults to an empty set.
+    ///              See `NSKeyValueObservingOptions` for available options.
+    ///   - changeHandler: A `@Sendable` closure that's executed with each new value.
+    ///
+    /// - Returns: An ``AsyncCancellable`` that can be stored and cancelled as needed.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// class ProgressObserver {
+    ///     var cancellables: Set<AnyAsyncCancellable> = []
+    ///     
+    ///     func observeProgress(_ progress: Progress) {
+    ///         progress.monitorValues(for: \.fractionCompleted) { fraction in
+    ///             print("Progress: \(fraction.formatted(.percent))")
+    ///         }.store(in: &cancellables)
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// - Note: This method is deprecated in iOS 18+ in favour of the non-`@Sendable` version
+    ///   which provides better actor isolation support.
+    func monitorValues<Value: Sendable>(
+        for keyPath: KeyPath<Self, Value>,
+        options: NSKeyValueObservingOptions = [],
+        changeHandler: @escaping @Sendable (Value) -> Void
+    ) -> any AsyncCancellable {
+        values(for: keyPath, options: options)
+            .monitor(changeHandler)
     }
 }

Sources/AsyncMonitor/ValueLocker.swift

@@ -0,0 +1,20 @@
+import Foundation
+
+final class ValueLocker<Value>: @unchecked Sendable {
+    private let lock = NSLock()
+    private var unsafeValue: Value
+
+    init(value: Value) {
+        unsafeValue = value
+    }
+
+    var value: Value {
+        lock.withLock { unsafeValue }
+    }
+
+    func modify(_ f: (inout Value) -> Void) {
+        lock.withLock {
+            f(&unsafeValue)
+        }
+    }
+}

Tests/AsyncMonitorTests/AnyAsyncCancellableTests.swift

@@ -0,0 +1,26 @@
+@testable import AsyncMonitor
+import Testing
+
+@MainActor class AnyAsyncCancellableTests {
+    var subject: AnyAsyncCancellable!
+
+    @Test func cancelsWhenReleased() {
+        let cancellable = TestCancellable()
+        subject = AnyAsyncCancellable(cancellable: cancellable)
+        #expect(!cancellable.isCancelled)
+
+        subject = nil
+
+        #expect(cancellable.isCancelled)
+    }
+
+    @Test func cancelsWhenCancelled() {
+        let cancellable = TestCancellable()
+        subject = AnyAsyncCancellable(cancellable: cancellable)
+        #expect(!cancellable.isCancelled)
+
+        subject.cancel()
+
+        #expect(cancellable.isCancelled)
+    }
+}

Tests/AsyncMonitorTests/AsyncCancellableTests.swift

@@ -0,0 +1,19 @@
+@testable import AsyncMonitor
+import Testing
+
+@MainActor class AsyncCancellableTests {
+    var cancellables: Set<AnyAsyncCancellable> = []
+
+    @Test func storeInsertsIntoSetAndKeepsSubjectAlive() throws {
+        var subject: TestCancellable? = TestCancellable()
+        weak var weakSubject: TestCancellable? = subject
+        try #require(subject).store(in: &cancellables)
+        #expect(cancellables.count == 1)
+        subject = nil
+        #expect(weakSubject != nil)
+
+        cancellables.removeAll()
+
+        #expect(weakSubject == nil)
+    }
+}

Tests/AsyncMonitorTests/AsyncMonitorTests.swift

@@ -2,7 +2,7 @@ import Foundation
 import Testing
 @testable import AsyncMonitor
 
-@MainActor class AsyncMonitorTests {
+class AsyncMonitorTests {
     let center = NotificationCenter()
     let name = Notification.Name("a random notification")
 
@@ -10,10 +10,12 @@ import Testing
 
     @Test func callsBlockWhenNotificationsArePosted() async throws {
         await withCheckedContinuation { [center, name] continuation in
-            subject = center.notifications(named: name).map(\.name).monitor { receivedName in
+            subject = center.notifications(named: name)
-                #expect(name == receivedName)
+                .map(\.name)
-                continuation.resume()
+                .monitor { receivedName in
-            }
+                    #expect(name == receivedName)
+                    continuation.resume()
+                }
             Task {
                 center.post(name: name, object: nil)
             }
@@ -21,21 +23,25 @@ import Testing
     }
 
     @Test func doesNotCallBlockWhenOtherNotificationsArePosted() async throws {
-        subject = center.notifications(named: name).map(\.name).monitor { receivedName in
+        subject = center.notifications(named: name)
-            Issue.record("Called for irrelevant notification \(receivedName)")
+            .map(\.name)
-        }
+            .monitor { receivedName in
-        Task {
+                Issue.record("Called for irrelevant notification \(receivedName)")
+            }
+        Task { [center] in
             center.post(name: Notification.Name("something else"), object: nil)
         }
         try await Task.sleep(for: .milliseconds(10))
     }
 
-    @Test func stopsCallingBlockWhenDeallocated() async throws {
+    @Test @MainActor func stopsCallingBlockWhenDeallocated() async throws {
-        subject = center.notifications(named: name).map(\.name).monitor { _ in
+        subject = center.notifications(named: name)
-            Issue.record("Called after deallocation")
+            .map(\.name)
-        }
+            .monitor { _ in
+                Issue.record("Called after deallocation")
+            }
 
-        Task {
+        Task { @MainActor in
             subject = nil
             center.post(name: name, object: nil)
         }
@@ -43,15 +49,16 @@ import Testing
         try await Task.sleep(for: .milliseconds(10))
     }
 
-    class Owner {
+    final class Owner: Sendable {
-        let deinitHook: () -> Void
+        let deinitHook: @Sendable () -> Void
 
-        private var cancellable: (any AsyncCancellable)?
+        nonisolated(unsafe) private var cancellable: (any AsyncCancellable)?
 
-        @MainActor init(center: NotificationCenter, deinitHook: @escaping () -> Void) {
+        init(center: NotificationCenter, deinitHook: @escaping @Sendable () -> Void) {
             self.deinitHook = deinitHook
             let name = Notification.Name("irrelevant name")
-            cancellable = center.notifications(named: name).map(\.name)
+            cancellable = center.notifications(named: name)
+                .map(\.name)
                 .monitor(context: self) { _, _ in }
         }
 
@@ -71,16 +78,36 @@ import Testing
         }
     }
 
+    final class SendableObject: NSObject, Sendable {}
+
     @Test func stopsCallingBlockWhenContextIsDeallocated() async throws {
-        var context: NSObject? = NSObject()
+        var context: SendableObject? = SendableObject()
-        subject = center.notifications(named: name).map(\.name)
+        subject = center.notifications(named: name)
+            .map(\.name)
             .monitor(context: context!) { context, receivedName in
                 Issue.record("Called after context was deallocated")
             }
         context = nil
-        Task {
+        Task { [center, name] in
             center.post(name: name, object: nil)
         }
         try await Task.sleep(for: .milliseconds(10))
     }
+
+    @Test func equatable() throws {
+        let subject = AsyncMonitor(sequence: AsyncStream.just(42)) { _ in }
+        #expect(subject == subject)
+        #expect(subject != AsyncMonitor(sequence: AsyncStream.just(42)) { _ in })
+    }
+
+    @Test func hashable() throws {
+        let subjects = (1...100).map { _ in
+            AsyncMonitor(sequence: AsyncStream.just(42)) { _ in }
+        }
+        var hashValues: Set<Int> = []
+        for subject in subjects {
+            hashValues.insert(subject.hashValue)
+        }
+        #expect(hashValues.count == subjects.count)
+    }
 }

Tests/AsyncMonitorTests/AsyncSequence+Just.swift

@@ -0,0 +1,9 @@
+import Foundation
+
+extension AsyncSequence where Element: Sendable {
+    static func just(_ value: Element) -> AsyncStream<Element> {
+        AsyncStream { continuation in
+            continuation.yield(value)
+        }
+    }
+}

Tests/AsyncMonitorTests/NSObject+AsyncKVOTests.swift

@@ -0,0 +1,53 @@
+@testable import AsyncMonitor
+import Foundation
+import Testing
+
+class AsyncKVOTests {
+    var subject: Progress? = Progress(totalUnitCount: 42)
+    var cancellable: (any AsyncCancellable)?
+
+    @Test(.timeLimit(.minutes(1)))
+    func monitorValuesYieldsChanges() async throws {
+        let subject = try #require(subject)
+        let values = ValueLocker(value: [Double]())
+        let total = 3
+        cancellable = subject.values(for: \.fractionCompleted)
+            .prefix(total)
+            .monitor { progress in
+                values.modify { $0.append(progress) }
+            }
+
+        for n in 1...total {
+            subject.completedUnitCount += 1
+            while values.value.count < n {
+                try await Task.sleep(for: .microseconds(2))
+            }
+        }
+
+        #expect(values.value.count == total)
+    }
+
+    // It's important that the test and the progress-observing task are not on the same actor, so
+    // we make the test @MainActor and observe progress values on another actor. Otherwise it's a
+    // deadlock.
+    @Test(.timeLimit(.minutes(1)))
+    @MainActor func valuesYieldsChanges() async throws {
+        let subject = try #require(subject)
+        let total = 3
+        let task = Task {
+            var values = [Double]()
+            for await progress in subject.values(for: \.fractionCompleted).prefix(total) {
+                values.append(progress)
+            }
+            return values
+        }
+        await Task.yield()
+
+        for _ in 1...total {
+            subject.completedUnitCount += 1
+        }
+        let values = await task.value
+
+        #expect(values.count == total)
+    }
+}

Tests/AsyncMonitorTests/ReadmeExamples.swift

@@ -1,20 +1,26 @@
 import Foundation
 @testable import AsyncMonitor
 
-@MainActor class SimplestVersion {
+// MARK: Basics
+
+extension Notification: @unchecked @retroactive Sendable {}
+
+class SimplestVersion {
     let cancellable = NotificationCenter.default
-        .notifications(named: .NSCalendarDayChanged).map(\.name)
+        .notifications(named: .NSCalendarDayChanged)
+        .map(\.name)
         .monitor { _ in
             print("The date is now \(Date.now)")
         }
 }
 
-@MainActor class WithContext {
+final class WithContext: Sendable {
-    var cancellables = Set<AnyAsyncCancellable>()
+    nonisolated(unsafe) var cancellables: Set<AnyAsyncCancellable> = []
 
     init() {
         NotificationCenter.default
-            .notifications(named: .NSCalendarDayChanged).map(\.name)
+            .notifications(named: .NSCalendarDayChanged)
+            .map(\.name)
             .monitor(context: self) { _self, _ in
                 _self.dayChanged()
             }.store(in: &cancellables)
@@ -24,3 +30,33 @@ import Foundation
         print("The date is now \(Date.now)")
     }
 }
+
+// MARK: - Combine
+
+@preconcurrency import Combine
+
+class CombineExample {
+    var cancellables: Set<AnyAsyncCancellable> = []
+
+    init() {
+        Timer.publish(every: 1.0, on: .main, in: .common)
+            .autoconnect()
+            .values
+            .monitor { date in
+                print("Timer fired at \(date)")
+            }.store(in: &cancellables)
+    }
+}
+
+// MARK: - KVO
+
+class KVOExample {
+    var cancellables: Set<AnyAsyncCancellable> = []
+
+    init() {
+        let progress = Progress(totalUnitCount: 42)
+        progress.monitorValues(for: \.fractionCompleted, options: [.initial, .new]) { fraction in
+            print("Progress is \(fraction.formatted(.percent))%")
+        }.store(in: &cancellables)
+    }
+}

Tests/AsyncMonitorTests/TestCancellable.swift

@@ -0,0 +1,20 @@
+import AsyncMonitor
+
+class TestCancellable: AsyncCancellable {
+    lazy var id = ObjectIdentifier(self)
+    var isCancelled = false
+
+    func cancel() {
+        isCancelled = true
+    }
+
+    // MARK: Hashable conformance
+
+    public static func == (lhs: TestCancellable, rhs: TestCancellable) -> Bool {
+        lhs.id == rhs.id
+    }
+
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(id)
+    }
+}