From f2e23ad41895ce925643bf8c0e34c4435e927199 Mon Sep 17 00:00:00 2001
From: Jakub Kiermasz <kiermasz.k@gmail.com>
Date: Mon, 12 Aug 2024 20:45:25 +0200
Subject: [PATCH] Start/stop engine when entering background/foreground (#70)

---
 Sources/Pow/Infrastructure/Haptics.swift | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/Sources/Pow/Infrastructure/Haptics.swift b/Sources/Pow/Infrastructure/Haptics.swift
index fb659ff..22acefb 100644
--- a/Sources/Pow/Infrastructure/Haptics.swift
+++ b/Sources/Pow/Infrastructure/Haptics.swift
@@ -5,8 +5,21 @@ import CoreHaptics
 
 internal struct Haptics {
     private static var engine: CHHapticEngine? = {
-        return try? CHHapticEngine()
+        let engine = try? CHHapticEngine()
+        addHapticEngineObservers()
+        return engine
     }()
+  
+    private static func addHapticEngineObservers() {
+        // Without stopping the CHHapticEngine when entering background mode, haptics are not played when the app enters the foreground.
+        // See https://github.com/EmergeTools/Pow/issues/69
+        NotificationCenter.default.addObserver(forName: UIApplication.didEnterBackgroundNotification, object: nil, queue: nil) { _ in
+            engine?.stop()
+        }
+        NotificationCenter.default.addObserver(forName: UIApplication.willEnterForegroundNotification, object: nil, queue: nil) { _ in
+            try? engine?.start()
+        }
+    }
 
     private static var supportsHaptics = CHHapticEngine.capabilitiesForHardware().supportsHaptics