Add audio activation settings to iOS

iOS/GBSettingsViewController.m

@@ -283,6 +283,15 @@ static NSString const *typeLightTemp = @"typeLightTemp";
     ];
     
     NSArray<NSDictionary *> *audioMenu = @[
+        @{
+            @"header": @"Enable Audio",
+            @"items": @[
+                @{@"type": typeRadio, @"pref": @"GBAudioMode", @"title": @"Never",                     @"value": @"off",},
+                @{@"type": typeRadio, @"pref": @"GBAudioMode", @"title": @"Controlled by Silent Mode", @"value": @"switch",},
+                @{@"type": typeRadio, @"pref": @"GBAudioMode", @"title": @"Always",                    @"value": @"on",},
+            ],
+
+        },
         @{
             @"header": @"High-pass Filter",
             @"items": @[

iOS/GBViewController.m

@@ -143,6 +143,13 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     [self addDefaultObserver:^(id newValue) {
         GB_set_rewind_length(gb, [newValue unsignedIntValue]);
     } forKey:@"GBRewindLength"];
+    [self addDefaultObserver:^(id newValue) {
+        [[AVAudioSession sharedInstance] setCategory:[newValue isEqual:@"on"]? AVAudioSessionCategoryPlayback :  AVAudioSessionCategorySoloAmbient
+                                                mode:AVAudioSessionModeMeasurement // Reduces latency on BT
+                                  routeSharingPolicy:AVAudioSessionRouteSharingPolicyDefault
+                                             options:AVAudioSessionCategoryOptionAllowBluetoothA2DP | AVAudioSessionCategoryOptionAllowAirPlay
+                                               error:nil];
+    } forKey:@"GBAudioMode"];
 }
 
 - (void)addDefaultObserver:(void(^)(id newValue))block forKey:(NSString *)key
@@ -526,6 +533,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
 {
     GB_set_pixels_output(&_gb, _gbView.pixels);
     GB_set_sample_rate(&_gb, 96000);
+    if (![[[NSUserDefaults standardUserDefaults] stringForKey:@"GBAudioMode"] isEqual:@"off"]) {
         _audioClient = [[GBAudioClient alloc] initWithRendererBlock:^(UInt32 sampleRate, UInt32 nFrames, GB_sample_t *buffer) {
             [_audioLock lock];
             
@@ -557,6 +565,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
             }
             [_audioLock unlock];
         } andSampleRate:96000];
+    }
     
     [_audioClient start];
     if (GB_has_accelerometer(&_gb)) {

iOS/main.m

@@ -9,6 +9,7 @@ int main(int argc, char * argv[])
         [[NSUserDefaults standardUserDefaults] registerDefaults:@{
             @"GBFilter": @"NearestNeighbor",
             @"GBColorCorrection": @(GB_COLOR_CORRECTION_MODERN_BALANCED),
+            @"GBAudioMode": @"switch",
             @"GBHighpassFilter": @(GB_HIGHPASS_ACCURATE),
             @"GBRewindLength": @(10),
             @"GBFrameBlendingMode": @(GB_FRAME_BLENDING_MODE_ACCURATE),