cocoalibspotify: Crash during playback callback under music_delivery

Question

We have crashes when playing using cocoalibspotify: The problem looks like that in the callback function music_delivery() under SPSession.m, the instance initiated callback is not a SPSessionAudioDeliveryDelegate compatible instance. However, the only playback related instance we used is SPPlaybackManager. And the function we used to play the song using spotify is:

#pragma mark - Domain function
- (void)searchForKeywords:(NSString *)keywords{
    //construct search string
    SPSearch *search = [[SPSearch alloc] initWithSearchQuery:keywords inSession:[SPSession sharedSession]];

    //search track
    [SPAsyncLoading waitUntilLoaded:search timeout:kSPAsyncLoadingDefaultTimeout then:^(NSArray *results, NSArray *notLoadedResults) {
    if ([results count]>0) {
        //search returns results.
        SPSearch *thisSearch = [results objectAtIndex:0];
        if ([[thisSearch tracks] count]>0) {

            // Add loading flag for album art
            [[ImageManager sharedInstance] setLoadingFlagForSong:self.namedSong];

            SPTrack *track = [[thisSearch tracks]objectAtIndex:0];

            [SPAsyncLoading waitUntilLoaded:track timeout:kSPAsyncLoadingDefaultTimeout then:^(NSArray *tracks, NSArray *notLoadedTracks) {

                self.currentTrack = track;
            }];
        }else{
        }

    }else{
        //search didn't return results.
    }
    }];
}

- (void)play
{
[SPSession dispatchToLibSpotifyThread:^{
    [[SPSession sharedSession]setPlaybackDelegate:self];

    // Change the current track of the session
    if (currentTrack) {

        self.playbackManager = [[SPPlaybackManager alloc] initWithPlaybackSession:[SPSession sharedSession]];
        [[SPSession sharedSession]setPlaybackDelegate:self];

        [self.playbackManager playTrack:currentTrack callback:^(NSError *error) {

            // Failure playing
            if (error) {
            }
            // Success
        }];
    }

    // Play
    else {
    }
}];
}

- (void)pause
{
[SPSession dispatchToLibSpotifyThread:^{
    [SpotifyHelper sharedInstance].playbackManager.isPlaying = NO;
} waitUntilDone:YES];
}


- (void)stop
{
[SPSession dispatchToLibSpotifyThread:^{
    [SpotifyHelper sharedInstance].playbackManager.isPlaying = NO;
    [[SpotifyHelper sharedInstance].playbackManager sessionDidEndPlayback:[SPSession sharedSession]];
} waitUntilDone:YES];
}

-(void)seekToLocation:(float)location
{
[SPSession dispatchToLibSpotifyThread:^{
    [[SpotifyHelper sharedInstance].playbackManager seekToTrackPosition:location * self.currentTrack.duration];
} waitUntilDone:YES];
}

The error message: -[__NSCFType session:shouldDeliverAudioFrames:ofCount:streamDescription:]: unrecognized selector sent to instance 0x21328a90

Stack:
0    libsystem_kernel.dylib  __pthread_kill + 8
1    libsystem_c.dylib   pthread_kill + 58
2    libsystem_c.dylib   abort + 94
3    libc++abi.dylib     abort_message + 74
4    libc++abi.dylib     default_terminate() + 24
5    libobjc.A.dylib     _objc_terminate() + 146
6    libc++abi.dylib     safe_handler_caller(void (*)()) + 78
7    libc++abi.dylib     std::terminate() + 19
8    libc++abi.dylib     __cxa_throw + 122
9    libobjc.A.dylib     objc_exception_throw + 94
10   CoreFoundation  __methodDescriptionForSelector
11   CoreFoundation  ___forwarding___ + 392
12   CoreFoundation  _CF_forwarding_prep_0 + 24
crash->13    OURAPP      music_delivery
14   OURAPP  sp_playlist_get_offline_download_completed
15   OURAPP  sp_error_message
16   OURAPP  sp_error_message

Answer 1

Two things:

1) Don't dispatch to the CocoaLibSpotify thread when calling CocoaLibSpotify methods — that's done internally. Remove the dispatchToLibSpotifyThread line.

2) Remove the [[SPSession sharedSession]setPlaybackDelegate:self]; line. That's what's causing your crash.