我正在尝试使用 AVAudioEngine 播放 AVAudioFile。代码大部分取自 Apple Developer 的在线视频并改编，但没有播放。花了一些时间浏览论坛，但似乎没有任何亮点。
我有两种方法。第一个调用标准打开文件对话框，打开音频文件，分配一个 AVAudioBuffer 对象（我稍后会用到）并用音频数据填充它。第二个设置 AVAudioEngine 和 AVAudioPlayerNode 对象，将所有内容连接起来并播放文件。下面列出了这两种方法。
- (IBAction)getSoundFileAudioData:(id)sender {
NSOpenPanel* openPanel = [NSOpenPanel openPanel];
openPanel.title = @"Choose a .caf file";
openPanel.showsResizeIndicator = YES;
openPanel.showsHiddenFiles = NO;
openPanel.canChooseDirectories = NO;
openPanel.canCreateDirectories = YES;
openPanel.allowsMultipleSelection = NO;
openPanel.allowedFileTypes = @[@"caf"];
[openPanel beginWithCompletionHandler:^(NSInteger result){
if (result == NSFileHandlingPanelOKButton) {
NSURL* theAudioFileURL = [[openPanel URLs] objectAtIndex:0];
// Open the document.
theAudioFile = [[AVAudioFile alloc] initForReading:theAudioFileURL error:nil];
AVAudioFormat *format = theAudioFile.processingFormat;
AVAudioFrameCount capacity = (AVAudioFrameCount)theAudioFile.length;
theAudioBuffer = [[AVAudioPCMBuffer alloc]
initWithPCMFormat:format frameCapacity:capacity];
NSError *error;
if (![theAudioFile readIntoBuffer:theAudioBuffer error:&error]) {
NSLog(@"problem filling buffer");
}
else
playOrigSoundFileButton.enabled = true;
}
}];}
- (IBAction)playSoundFileAudioData:(id)sender {
AVAudioEngine *engine = [[AVAudioEngine alloc] init]; // set up the audio engine
AVAudioPlayerNode *player = [[AVAudioPlayerNode alloc] init]; // set up a player node
[engine attachNode:player]; // attach player node to engine
AVAudioMixerNode *mixer = [engine mainMixerNode];
[engine connect:player to:mixer format:theAudioFile.processingFormat]; // connect player node to mixer
[engine connect:player to:mixer format:[mixer outputFormatForBus:0]]; // connect player node to mixer
NSError *error;
if (![engine startAndReturnError:&error]) {
NSLog(@"Problem starting engine ");
}
else {
[player scheduleFile:theAudioFile atTime: nil completionHandler:nil];
[player play];
}
}
我检查了功能正在执行，音频引擎正在运行并且音频文件已被读取。我也尝试过使用不同的音频文件格式，包括单声道和立体声。有任何想法吗？
我正在运行 Xcode 7.3.1。