In-App notifications don't pause background audio

// FREEBIE

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -3203,7 +3203,7 @@ typedef enum : NSUInteger {
     NSURL *fileURL = [NSURL fileURLWithPath:filepath];
 
     // Setup audio session
-    BOOL configuredAudio = [OWSAudioSession.shared setRecordCategoryWithAudioActivity:self.voiceNoteAudioActivity];
+    BOOL configuredAudio = [OWSAudioSession.shared startRecordingAudioActivity:self.voiceNoteAudioActivity];
     if (!configuredAudio) {
         OWSFail(@"%@ Couldn't configure audio session", self.logTag);
         [self cancelVoiceMemo];

SignalMessaging/attachments/OWSVideoPlayer.swift

@@ -38,7 +38,7 @@ public class OWSVideoPlayer: NSObject {
     }
 
     public func play() {
-        OWSAudioSession.shared.setPlaybackCategory(audioActivity: self.audioActivity)
+        OWSAudioSession.shared.startPlaybackAudioActivity(self.audioActivity)
 
         guard let item = avPlayer.currentItem else {
             owsFail("\(logTag) video player item was unexpectedly nil")

SignalMessaging/environment/OWSAudioSession.swift

@@ -33,13 +33,23 @@ public class OWSAudioSession: NSObject {
 
     private var currentActivities: [Weak<AudioActivity>] = []
 
-    // Ignores hardware mute switch, plays through external speaker
-    public func setPlaybackCategory(audioActivity: AudioActivity) {
+    // Respects hardware mute switch, plays through external speaker, mixes with backround audio
+    // appropriate for foreground sound effects.
+    public func startAmbientAudioActivity(_ audioActivity: AudioActivity) {
+        Logger.debug("\(logTag) in \(#function)")
+        
+        startAudioActivity(audioActivity)
+        
+        do {
+            try avAudioSession.setCategory(AVAudioSessionCategoryAmbient)
+        } catch {
+            owsFail("\(logTag) in \(#function) failed with error: \(error)")
+        }
+    }
+    
+    // Ignores hardware mute switch, plays through external speaker
+    public func startPlaybackAudioActivity(_ audioActivity: AudioActivity) {
         Logger.debug("\(logTag) in \(#function)")
-
-        // In general, we should have put the audio session back to it's default
-        // category when we were done with whatever activity required it to be modified
-        assert(avAudioSession.category == AVAudioSessionCategorySoloAmbient)
 
         startAudioActivity(audioActivity)
 
@@ -50,13 +60,9 @@ public class OWSAudioSession: NSObject {
         }
     }
 
-    public func setRecordCategory(audioActivity: AudioActivity) -> Bool {
+    public func startRecordingAudioActivity(_ audioActivity: AudioActivity) -> Bool {
         Logger.debug("\(logTag) in \(#function)")
 
-        // In general, we should have put the audio session back to it's default
-        // category when we were done with whatever activity required it to be modified
-        assert(avAudioSession.category == AVAudioSessionCategorySoloAmbient)
-
         assert(avAudioSession.recordPermission() == .granted)
 
         startAudioActivity(audioActivity)
@@ -104,8 +110,6 @@ public class OWSAudioSession: NSObject {
         }
 
         do {
-            try avAudioSession.setCategory(AVAudioSessionCategorySoloAmbient)
-
             // When playing audio in Signal, other apps audio (e.g. Music) is paused.
             // By notifying when we deactivate, the other app can resume playback.
             try avAudioSession.setActive(false, with: [.notifyOthersOnDeactivation])

SignalMessaging/environment/OWSSounds.m

@@ -224,7 +224,7 @@ NSString *const kOWSSoundsStorageGlobalNotificationKey = @"kOWSSoundsStorageGlob
     [self.audioPlayer stop];
     self.audioPlayer = [OWSSounds audioPlayerForSound:sound quiet:quiet];
     if (shouldRespectSilentSwitch) {
-        [self.audioPlayer playWithCurrentAudioCategory];
+        [self.audioPlayer playWithAmbientAudioCategory];
     } else {
         [self.audioPlayer playWithPlaybackAudioCategory];
     }

SignalMessaging/utils/OWSAudioPlayer.h

@@ -38,6 +38,9 @@ typedef NS_ENUM(NSInteger, AudioPlaybackState) {
 // respects silent switch
 - (void)playWithCurrentAudioCategory;
 
+// respects silent switch, mixes with others
+- (void)playWithAmbientAudioCategory;
+
 // will ensure sound is audible, even if silent switch is enabled
 - (void)playWithPlaybackAudioCategory;
 

SignalMessaging/utils/OWSAudioPlayer.m

@@ -99,7 +99,15 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)playWithPlaybackAudioCategory
 {
     OWSAssertIsOnMainThread();
-    [OWSAudioSession.shared setPlaybackCategoryWithAudioActivity:self.audioActivity];
+    [OWSAudioSession.shared startPlaybackAudioActivity:self.audioActivity];
+
+    [self play];
+}
+
+- (void)playWithAmbientAudioCategory
+{
+    OWSAssertIsOnMainThread();
+    [OWSAudioSession.shared startAmbientAudioActivity:self.audioActivity];
 
     [self play];
 }