使用相同的方法更新UILabel两次

Question

我在查找热门时遇到一些麻烦,在一次动作中两次更新UILabel.基本上用户点击播放按钮来听到声音.当声音播放时,"消息1"出现在UILabel中.当声音完成播放时,"消息2"出现在同一标签中.当我运行此标签时,标签直接转到"消息2".

.H

@interface ViewController : UIViewController
<AVAudioRecorderDelegate, AVAudioPlayerDelegate>
{
AVAudioPlayer *audioPlayer;
UIButton *playButton;
UILabel *answerLabel;

}
@property (nonatomic, retain) IBOutlet UIButton *playButton;
@property (nonatomic, retain) IBOutlet UILabel *answerLabel;
-(IBAction) play;
@end

.M

-(IBAction) play
{    
        int length = [audioPlayer duration];
        [audioPlayer play];
        answerLabel.text = @"Message 1";
        [NSThread sleepForTimeInterval:length];
        answerLabel.text = @"Message 2";   
}

Answer 1

我看到你实现了AVAudioPlayerDelegate协议,所以我假设在某些时候你将播放器的委托设置为self

如果是这种情况,请将播放方法更改为以下内容:

-(IBAction) play
{    
    [audioPlayer play];
    answerLabel.text = @"Message 1";
}

然后实现此方法:

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
    answerLabel.text = @"Message 2";
}