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我AVAudioplayer用来播放音频文件，播放/暂停按钮在播放和暂停之间切换，以及一个NSTimer接一个audio player地同步view controllers。我总共有 10 或 11 个view controllers要一个接一个地加载。

当播放按钮第一次被按下时，它NSTimer开始播放，audio file并且基于NSTimer，视图控制器将一个接一个地加载。当再次按下暂停按钮以恢复时，它会从该点音频文件恢复所有内容，NSTimer并view controllers从暂停的同一点恢复，这很好。但是，同时它开始view controllers从头开始一个接一个地加载，NSTimer这是不好的。

它正在使用此语句重新加载视图控制器

self.timer = [NSTimer scheduledTimerWithTimeInterval:11.0
                                              target:self
                                            selector:@selector(displayviewsAction:)
                                            userInfo:nil
                                             repeats:NO];

view controllers所以我的问题是，当再次按下暂停按钮以恢复播放时，我需要从头开始再次停止加载。

-(void)playpauseAction:(id)sender 
{ 
    if ([audioPlayer isPlaying]) {
        [sender setImage:[UIImage imageNamed:@"Play Icon.png"] forState:UIControlStateSelected];
        [audioPlayer pause];
        [self pauseTimer];
    } else {
        [sender setImage:[UIImage imageNamed:@"pause.png"] forState:UIControlStateNormal];
        [audioPlayer play];
        [self resumeTimer];
        self.timer = [NSTimer scheduledTimerWithTimeInterval:11.0
                                                      target:self
                                                    selector:@selector(displayviewsAction:)
                                                    userInfo:nil
                                                     repeats:NO];
    }       
}

-(void)pauseTimer{
    pauseStart = [[NSDate dateWithTimeIntervalSinceNow:0] retain];
    previousFireDate = [[timer fireDate] retain];
    [timer setFireDate:[NSDate distantFuture]];
}

-(void)resumeTimer{
    float pauseTime = -1*[pauseStart timeIntervalSinceNow];
    [timer setFireDate:[previousFireDate initWithTimeInterval:pauseTime sinceDate:previousFireDate]];
    [pauseStart release];
    [previousFireDate release];    
}

- (void)displayviewsAction:(id)sender
{  
    First *firstController = [[First alloc] init];
    firstController.view.frame = CGRectMake(0, 0, 320, 480);
    CATransition *transitionAnimation = [CATransition animation];  
    [transitionAnimation setDuration:1];    
    [transitionAnimation setType:kCATransitionFade];    
    [transitionAnimation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn]];    
    [self.view.layer addAnimation:transitionAnimation forKey:kCATransitionFade];
    [self.view addSubview:firstController.view];
    [self.view addSubview:toolbar];
    [firstController release];   
    self.timer = [NSTimer scheduledTimerWithTimeInterval:23 target:self selector:@selector(Second) userInfo:nil repeats:NO];     
 }

view controllers当再次按下暂停按钮以恢复播放时，任何人都可以提供有关如何从头开始再次停止加载的想法。

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1 回答 1

0

我收集到您正在尝试FirstViewController在音轨中经过 11 秒后显示。
您可以将计时器设置为轮询（每 0.5 - 1.0 秒），如果 audioPlayer 的经过时间大于 11.0，则执行您的操作。

-(void)playpauseAction:(id)sender 
{ 
if ([audioPlayer isPlaying]){
   [sender setImage:[UIImage imageNamed:@"Play Icon.png"] forState:UIControlStateSelected];
   [audioPlayer pause];
   [self.timer invalidate]; // stop the polling timer
} else {
   [sender setImage:[UIImage imageNamed:@"pause.png"] forState:UIControlStateNormal];
   [audioPlayer play];
   // start/resume the timer
   self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 /* polling interval */
                                                      target:self
                                                   selector:@selector(tryToDisplayViews:)
                                                    userInfo:nil
                                                     repeats:YES]; /* REPEAT = YES */
}       
}

// the new polled method
-(void)tryToDisplayViews:(id)sender {
    // need last current time as a new variable to ensure that we only add the view once
    // and not every time the method fires with currentTime > 11.0
    if( audioPlayer.currentTime > 11.0 && lastCurrentTime < 11.0) {
        [self displayviewsAction:nil];
    } 
    // you can add the second view here in a similar fashion
    // if(audioPlayer.currentTime > (23.0+11.0) && lastCurrentTime < (23.0+11.0) ) {}

    lastCurrentTime = audioPlayer.currentTime;

}

这也摆脱了你的resumeTimer/pauseTimer动作，你不需要计算暂停的时间。

于 2012-06-15T18:56:22.110 回答