Adds ability to switch the local cache directory

Xcodes/Backend/AppState.swift

@@ -55,6 +55,13 @@ class AppState: ObservableObject {
 
     @Published var error: Error?
     @Published var authError: Error?
+    
+    // MARK: Advanced Preferences
+    @Published var localPath = "" {
+        didSet {
+            Current.defaults.set(localPath, forKey: "localPath")
+        }
+    }
 
     // MARK: - Publisher Cancellables
     
@@ -84,6 +91,11 @@ class AppState: ObservableObject {
         try? loadCachedAvailableXcodes()
         checkIfHelperIsInstalled()
         setupAutoInstallTimer()
+        setupDefaults()
+    }
+    
+    func setupDefaults() {
+        localPath = Current.defaults.string(forKey: "localPath") ?? Path.defaultXcodesApplicationSupport.string
     }
     
     // MARK: Timer
@@ -393,6 +405,11 @@ class AppState: ObservableObject {
         guard let installedXcode = Current.files.installedXcodes(Path.root/"Applications").first(where: { $0.version == id }) else { return }
         NSWorkspace.shared.activateFileViewerSelecting([installedXcode.path.url])
     }
+    
+    func reveal(path: String) {
+        let url = URL(fileURLWithPath: path)
+        NSWorkspace.shared.activateFileViewerSelecting([url])
+    }
 
     /// Make an Xcode active, a.k.a select it, in the `xcode-select` sense.
     ///

Xcodes/Backend/Path+.swift

@@ -1,6 +1,19 @@
 import Path
+import Foundation
 
 extension Path {
-    static let xcodesApplicationSupport = Path.applicationSupport/"com.robotsandpencils.XcodesApp"
-    static let cacheFile = xcodesApplicationSupport/"available-xcodes.json"
+    static let defaultXcodesApplicationSupport = Path.applicationSupport/"com.robotsandpencils.XcodesApp"
+    static var xcodesApplicationSupport: Path {
+        guard let savedApplicationSupport = Current.defaults.string(forKey: "localPath") else {
+            return defaultXcodesApplicationSupport
+        }
+        guard let path = Path(savedApplicationSupport) else {
+            return defaultXcodesApplicationSupport
+        }
+        return path
+    }
+    
+    static var cacheFile: Path {
+        return xcodesApplicationSupport/"available-xcodes.json"
+    }
 }

Xcodes/Frontend/Preferences/AdvancedPreferencePane.swift

@@ -1,13 +1,52 @@
 import AppleAPI
 import SwiftUI
+import Path
 
 struct AdvancedPreferencePane: View {
     @EnvironmentObject var appState: AppState
+   
     @AppStorage("dataSource") var dataSource: DataSource = .xcodeReleases
     @AppStorage("downloader") var downloader: Downloader = .aria2
     
     var body: some View {
         VStack(alignment: .leading, spacing: 20) {
+            
+            GroupBox(label: Text("Local Cache Path")) {
+                VStack(alignment: .leading) {
+                    HStack(alignment: .top, spacing: 5) {
+                        Text(appState.localPath).font(.footnote)
+                        .fixedSize(horizontal: false, vertical: true)
+                        .lineLimit(2)
+                        Button(action: { appState.reveal(path: appState.localPath) }) {
+                            Image(systemName: "arrow.right.circle.fill")
+                        }
+                        .buttonStyle(PlainButtonStyle())
+                        .help("Reveal in Finder")
+                        .fixedSize()
+                    }
+                    Button("Change") {
+                        let panel = NSOpenPanel()
+                        panel.allowsMultipleSelection = false
+                        panel.canChooseDirectories = true
+                        panel.canChooseFiles = false
+                        panel.canCreateDirectories = true
+                        panel.allowedContentTypes = [.folder]
+                        panel.directoryURL = URL(fileURLWithPath: appState.localPath)
+                        
+                        if panel.runModal() == .OK {
+                           
+                            guard let pathURL = panel.url, let path = Path(url: pathURL) else { return }
+                            self.appState.localPath = path.string
+                        }
+                    }
+                    Text("Xcodes caches available Xcode versions and temporary downloads new versions to a directory")
+                        .font(.footnote)
+                        .fixedSize(horizontal: false, vertical: true)
+                }
+                
+            }
+            .groupBoxStyle(PreferencesGroupBoxStyle())
+            
             GroupBox(label: Text("Data Source")) {
                 VStack(alignment: .leading) {
                     Picker("Data Source", selection: $dataSource) {
@@ -66,7 +105,7 @@ struct AdvancedPreferencePane: View {
             }
             .groupBoxStyle(PreferencesGroupBoxStyle())
         }
-        .frame(width: 400)
+        .frame(width: 500)
     }
     
     private var dataSourceFootnote: NSAttributedString {

Xcodes/Frontend/Preferences/GeneralPreferencePane.swift

@@ -21,7 +21,7 @@ struct GeneralPreferencePane: View {
             }
             .groupBoxStyle(PreferencesGroupBoxStyle())
         }
-        .frame(width: 400)
+        .frame(width: 500)
     }
 }
 

Xcodes/Frontend/Preferences/UpdatesPreferencePane.swift

@@ -50,7 +50,7 @@ struct UpdatesPreferencePane: View {
             }
             .groupBoxStyle(PreferencesGroupBoxStyle())
         }
-        .frame(width: 400)
+        .frame(width: 500)
     }
     
     private var lastUpdatedString: String {