Question

I’m currently downloading an .mp3 file from a remote server and once the file has loaded, I store it in the Caches directory. Then I create an instance of AVAudioPlayer and load the data into it:

- (void)playAudio:(NSString *)path
{
    NSLog(@"start playing audio at path %@", path);
    NSError *error = nil;
    NSData *audioData = [NSData dataWithContentsOfFile:path];
    _audioPlayer = [[AVAudioPlayer alloc] initWithData:audioData error:&error];
    if (error == nil)
    {
        [_audioPlayer play];    
    }
}

During the time that this file starts to play, some animation is also happening. If I allow the AVAudioPlayer to start playing, it seems to block the UI and the animation is frozen until the song has played for a second or two. This is on the simulator, FYI. I’m wondering if it has anything to do with the (possible) bugs/logs that AVAudio spits out when you start playing? Is there any way to play an audio file without affecting the UI/animation?

If I comment out [_audioPlayer play], the animation runs fine, so the problem doesn’t seem to be in the initWithData: call.

Here are the iOS 5 logged issues as well:

2012-01-05 14:32:27.427 Lovebind[53526:207] Error loading /System/Library/Extensions/AudioIPCDriver.kext/Contents/Resources/AudioIPCPlugIn.bundle/Contents/MacOS/AudioIPCPlugIn:  dlopen(/System/Library/Extensions/AudioIPCDriver.kext/Contents/Resources/AudioIPCPlugIn.bundle/Contents/MacOS/AudioIPCPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.433 Lovebind[53526:207] Error loading /System/Library/Extensions/AudioIPCDriver.kext/Contents/Resources/AudioIPCPlugIn.bundle/Contents/MacOS/AudioIPCPlugIn:  dlopen(/System/Library/Extensions/AudioIPCDriver.kext/Contents/Resources/AudioIPCPlugIn.bundle/Contents/MacOS/AudioIPCPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.556 Lovebind[53526:207] Error loading /System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn:  dlopen(/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.562 Lovebind[53526:207] Error loading /System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn:  dlopen(/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.572 Lovebind[53526:207] Error loading /System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn:  dlopen(/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.578 Lovebind[53526:207] Error loading /System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn:  dlopen(/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.589 Lovebind[53526:207] Error loading /System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn:  dlopen(/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security
2012-01-05 14:32:27.595 Lovebind[53526:207] Error loading /System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn:  dlopen(/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAHALPlugIn.bundle/Contents/MacOS/AppleHDAHALPlugIn, 262): Symbol not found: _CFXMLNodeGetInfoPtr
  Referenced from: /System/Library/Frameworks/Security.framework/Versions/A/Security
  Expected in: /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
 in /System/Library/Frameworks/Security.framework/Versions/A/Security

Answer 1

Actually, I’ll turn my comments (now deleted) into an official answer:

1) your “Error loading” lines should go away when you add CoreFoundation.framework to your project.

and

2) play your sound on a separate thread and I suspect your blocking issues will go away.

The easiest way to make this happen is to do:

- (void)playingAudioOnSeparateThread: (NSString *) path
{
    if(_audioPlayer)
    {
       [_audioPlayer release];
       _audioPlayer = nil; // doing this while a sound is playing might crash... 
    }

    NSLog(@"start playing audio at path %@", path);
    NSError *error = nil;
    NSData *audioData = [NSData dataWithContentsOfFile:path];
    _audioPlayer = [[AVAudioPlayer alloc] initWithData:audioData error:&error];
    if (error == nil)
    {
        [_audioPlayer play];    
    }
}

- (void)playAudio:(NSString *)path
{
   [NSThread detachNewThreadSelector: @selector(playingAudioOnSeparateThread:) toTarget: self withObject: path];
}

I have not checked this code for sanity or error checking. That’s your job. 🙂