声音播放完毕后执行代码的最佳方式

Question

我希望在声音播放完毕后执行一些代码，但不知道最好的方法是什么。我看过performSelectorOnMainThread....，但并不完全理解——即使那样，我也不确定这是否是解决问题的最佳方法。我想在播放完声音后更改标签的文本颜色。我会很感激一些帮助。我的代码如下：

-(void) playWordSound:(UILabel *)label
{
    NSString *path;
    SystemSoundID soundId;
    switch (label.tag)
    {
        case 1:
            path = [[NSBundle mainBundle] pathForResource:@"humpty" ofType:@"wav"];
            break;
        case 2:
            path = [[NSBundle mainBundle] pathForResource:@"dumpty" ofType:@"wav"];
            break;
        case 3:
            path = [[NSBundle mainBundle] pathForResource:@"saty" ofType:@"wav"];
            break;
        case 4:
            path = [[NSBundle mainBundle] pathForResource:@"on 2" ofType:@"wav"];
            break;
        case 5:
            path = [[NSBundle mainBundle] pathForResource:@"a 3" ofType:@"wav"];
            break;
        case 6:
            path = [[NSBundle mainBundle] pathForResource:@"wall" ofType:@"wav"];
            break;
    }
        NSURL *url = [NSURL fileURLWithPath:path];
        AudioServicesCreateSystemSoundID( (CFURLRef)objc_unretainedPointer(url), &soundId);
    AudioServicesPlaySystemSound(soundId); 
    //this is where i want to change the color of the label
}

Answer 1

使用 AVPlayerItem 并为事件 AVPlayerItemDidPlayToEndTimeNotification 添加观察者。

例如

...

AVPlayerItem* playerItem = [AVPlayerItem playerItemWithAsset:asset];
[playerItem addObserver:self forKeyPath:@"status" options:0 context:&ItemStatusContext];
[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(playerItemDidReachEnd:)
                                             name:AVPlayerItemDidPlayToEndTimeNotification
                                             object:playerItem];
player = [AVQueuePlayer playerWithPlayerItem:playerItem];
[player play];

...

- (void)playerItemDidReachEnd:(NSNotification *)notification {
    // Do stuff here
}

....

Answer 2

这个方法可以帮到你：

OSStatus AudioServicesAddSystemSoundCompletion (
   SystemSoundID                           inSystemSoundID,
   CFRunLoopRef                            inRunLoop,
   CFStringRef                             inRunLoopMode,
   AudioServicesSystemSoundCompletionProc  inCompletionRoutine,
   void                                    *inClientData
);