Question

My application plays online streams.

However when user navigates to the next view controller the music stops. Here is the code that plays sound:

- (void)start
{
    @synchronized (self)
    {
        if (state == AS_PAUSED)
        {
            [self pause];
        }
        else if (state == AS_INITIALIZED)
        {
            NSAssert([[NSThread currentThread] isEqual:[NSThread mainThread]],
                @"Playback can only be started from the main thread.");
            notificationCenter =
                [[NSNotificationCenter defaultCenter] retain];
            self.state = AS_STARTING_FILE_THREAD;
            internalThread =
                [[NSThread alloc]
                    initWithTarget:self
                    selector:@selector(startInternal)
                    object:nil];
            [internalThread setName:@"InternalThread"];
            [internalThread start];
        }
    }
}

I’ve tried :

dispatch_async(dispatch_get_main_queue(), 
                           ^{
                               [internalThread start];
                           });

But it doesn’t work. Does anyone have experience with this?

Answer 1

You have to keep a reference to your AS object.

In my case, I’ve wrapped AS in a singleton.

@implementation MyClass

static AudioStreamer *sharedStreamer = nil;

+(AudioStreamer *)sharedStreamer{
    return sharedStreamer;
}
-(void)play{
    playing=YES;
}

-(void)stop{
    playing=NO;
}    

-(IBAction)playStop{
    if (!self.playing)
    {       
        [self createStreamer];
        [[MyClass sharedStreamer] start];
    }
    else
    {
        [[MyClass sharedStreamer] stop];
    }

}    

- (void)viewDidLoad {
    [super viewDidLoad];

    if([MyClass sharedStreamer]){
        [[NSNotificationCenter defaultCenter]
         addObserver:self
         selector:@selector(playbackStateChanged:)
         name:ASStatusChangedNotification
         object:[MyClass sharedStreamer]];
        [self playbackStateChanged:nil];
    }
}

//
// createStreamer
//
// Creates or recreates the AudioStreamer object.
//
- (void)createStreamer{
    if ([MyClass sharedStreamer]){
        return;
    }

    [self destroyStreamer];

    NSString *escapedValue =
    [(NSString *)CFURLCreateStringByAddingPercentEscapes(
                                                             nil,
                                                         (CFStringRef)@"http://url.com"],
                                                         NULL,
                                                         NULL,
                                                         kCFStringEncodingUTF8)
     autorelease];

    NSURL *url = [NSURL URLWithString:escapedValue];
    sharedStreamer = [[AudioStreamer alloc] initWithURL:url];

    [[NSNotificationCenter defaultCenter]
     addObserver:self
     selector:@selector(playbackStateChanged:)
     name:ASStatusChangedNotification
     object:[MyClass sharedStreamer]];
}

//
// playbackStateChanged:
//
// Invoked when the AudioStreamer
// reports that its playback status has changed.
//
- (void)playbackStateChanged:(NSNotification *)aNotification {
    if ([[MyClass sharedStreamer] isWaiting]){
        playing = YES ;
    } else if ([[MyClass sharedStreamer] isPlaying]) {
        playing = YES;
    } else if ([[MyClass sharedStreamer] isIdle]) {
        playing = NO;
            [self destroyStreamer];
    }
}

//
// destroyStreamer
//
// Removes the streamer, the UI update timer and the change notification
//
- (void)destroyStreamer{
    if ([MyClass sharedStreamer]){
        [[NSNotificationCenter defaultCenter]
         removeObserver:self
         name:ASStatusChangedNotification
         object:[MyClass sharedStreamer]];

        [[MyClass sharedStreamer] stop];
        [sharedStreamer release];
        sharedStreamer = nil;
    }
}