Handle iOS audio session interruptions by reinitializing audio

Core/System.cpp

@@ -134,6 +134,13 @@ void Audio_Init() {
 	}
 }
 
+void Audio_Shutdown() {
+	if (audioInitialized) {
+		audioInitialized = false;
+		host->ShutdownSound();
+	}
+}
+
 bool IsOnSeparateCPUThread() {
 	if (cpuThread != nullptr) {
 		return cpuThreadID == std::this_thread::get_id();
@@ -290,8 +297,7 @@ void CPU_Shutdown() {
 	__KernelShutdown();
 	HLEShutdown();
 	if (coreParameter.enableSound) {
-		host->ShutdownSound();
-		audioInitialized = false;  // deleted in ShutdownSound
+		Audio_Shutdown();
 	}
 	pspFileSystem.Shutdown();
 	mipsr4k.Shutdown();

Core/System.h

@@ -77,6 +77,7 @@ void PSP_RunLoopFor(int cycles);
 void Core_UpdateDebugStats(bool collectStats);
 
 void Audio_Init();
+void Audio_Shutdown();
 
 bool IsOnSeparateCPUThread();
 bool IsAudioInitialised();

ios/AppDelegate.mm

@@ -1,21 +1,108 @@
 #import "AppDelegate.h"
 #import "ViewController.h"
 #import "base/NativeApp.h"
+#import "Core/System.h"
+#import "Core/Config.h"
+#import "Common/Log.h"
+
+#import <AVFoundation/AVFoundation.h>
 
 @implementation AppDelegate
+
+// This will be called when the user receives and dismisses a phone call
+// or other interruption to the audio session
+// Registered in application:didFinishLaunchingWithOptions:
+// for AVAudioSessionInterruptionNotification
+-(void) handleAudioSessionInterruption:(NSNotification *)notification {
+	NSNumber *interruptionType = notification.userInfo[AVAudioSessionInterruptionTypeKey];
+	
+	// Sanity check in case it's somehow not an NSNumber
+	if (![interruptionType respondsToSelector:@selector(unsignedIntegerValue)]) {
+		return;  // Lets not crash
+	}
+	
+	switch ([interruptionType unsignedIntegerValue]) {
+		case AVAudioSessionInterruptionTypeBegan:
+			INFO_LOG(SYSTEM, "ios audio session interruption beginning");
+			if (g_Config.bEnableSound) {
+				Audio_Shutdown();
+			}
+			break;
+			
+		case AVAudioSessionInterruptionTypeEnded:
+			INFO_LOG(SYSTEM, "ios audio session interruption ending");
+			if (g_Config.bEnableSound) {
+				/* 
+				 * Only try to reinit audio if in the foreground, otherwise
+				 * it may fail. Instead, trust that applicationDidBecomeActive
+				 * will do it later.
+				 */
+				if ([UIApplication sharedApplication].applicationState == UIApplicationStateActive) { 
+					Audio_Init();
+				}
+			}
+			break;
+			
+		default:
+			break;
+	};
+}
+
+// This will be called when the iOS's shared media process was reset 
+// Registered in application:didFinishLaunchingWithOptions:
+// for AVAudioSessionMediaServicesWereResetNotification
+-(void) handleMediaServicesWereReset:(NSNotification *)notification {
+	INFO_LOG(SYSTEM, "ios media services were reset - reinitializing audio");
+	
+	/*
+	 When media services were reset, Apple recommends:
+	 1) Dispose of orphaned audio objects (such as players, recorders, 
+	    converters, or audio queues) and create new ones
+	 2) Reset any internal audio states being tracked, including all 
+	    properties of AVAudioSession
+	 3) When appropriate, reactivate the AVAudioSession instance using the 
+	    setActive:error: method
+	 We accomplish this by shutting down and reinitializing audio
+	 */
+	
+	if (g_Config.bEnableSound) {
+		Audio_Shutdown();
+		Audio_Init();
+	}
+}
+
 -(BOOL) application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
 	self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
 	self.viewController = [[ViewController alloc] init];
+	
+	[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleAudioSessionInterruption:) name:AVAudioSessionInterruptionNotification object:[AVAudioSession sharedInstance]];
+	
+	[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleMediaServicesWereReset:) name:AVAudioSessionMediaServicesWereResetNotification object:nil];
+	
 	self.window.rootViewController = self.viewController;
 	[self.window makeKeyAndVisible];
+	
 	return YES;
 }
 
+-(void) dealloc {
+	[[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
 -(void) applicationWillResignActive:(UIApplication *)application {
+	if (g_Config.bEnableSound) {
+		Audio_Shutdown();
+	}
+	
 	NativeMessageReceived("lost_focus", "");	
 }
 
 -(void) applicationDidBecomeActive:(UIApplication *)application {
+	if (g_Config.bEnableSound) {
+		Audio_Init();
+	}
+	
 	NativeMessageReceived("got_focus", "");	
 }
-@end
+
+@end