iphone - 播放声音，等待播放完成并继续 (iphone)

Question

我是 iPhone 和 Objective C 的新手，到目前为止，我已经能够编写一些小示例。

我想播放声音，并在示例播放完毕后继续执行其余代码，即:

printf("hello");
playASound["file.wav"];
printf("world");

实际上我得到:打印你好，同时播放文件和打印世界但我想要的是:打印你好，播放文件，打印世界......所以，问题是我如何获得它？

谢谢

顺便说一句。这是 playASound 代码:

-(void) playASound: (NSString *) file {

    //Get the filename of the sound file:
    NSString *path = [NSString stringWithFormat:@"%@/%@",
                      [[NSBundle mainBundle] resourcePath],
                      file];

    SystemSoundID soundID;
    //Get a URL for the sound file
    NSURL *filePath = [NSURL fileURLWithPath:path isDirectory:NO];
    AudioServicesCreateSystemSoundID((CFURLRef)filePath, &soundID);
    //play the file
    AudioServicesPlaySystemSound(soundID);
}

Answer 1

来自documentation :

Discussion This function plays a short sound (30 seconds or less in duration). Because sound might play for several seconds, this function is executed asynchronously. To know when a sound has finished playing, call the AudioServicesAddSystemSoundCompletion function to register a callback function.

因此，您需要将函数分成两部分:一个调用 PlayASound 并打印“Hello”的函数，以及一个 called by the system 的函数。当声音播放完毕并打印“World”时。

// Change PlayASound to return the SystemSoundID it created
-(SystemSoundID) playASound: (NSString *) file {

    //Get the filename of the sound file:
    NSString *path = [NSString stringWithFormat:@"%@/%@",
                      [[NSBundle mainBundle] resourcePath],
                      file];

    SystemSoundID soundID;
    //Get a URL for the sound file
    NSURL *filePath = [NSURL fileURLWithPath:path isDirectory:NO];
    AudioServicesCreateSystemSoundID((CFURLRef)filePath, &soundID);
    //play the file
    AudioServicesPlaySystemSound(soundID);
    return soundID;
}

-(void)startSound
{
   printf("Hello");
    SystemSoundID id = [self playASound:@"file.wav"];
    AudioServicesAddSystemSoundCompletion (
       id,
       NULL,
       NULL,
       endSound,
       NULL
   );
}

void endSound (
   SystemSoundID  ssID,
   void           *clientData
)
{
   printf("world\n");
}

另请参阅docs for AudioServicesAddSystemSoundCompletion和 AudioServicesSystemSoundCompletionProc .