- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];    // Override point for customization after application launch.    self.window.backgroundColor = [UIColor whiteColor];    [self.window makeKeyAndVisible];        UISlider *slider = [[UISlider alloc] init];    slider.center = CGPointMake(160, 400);    slider.bounds = CGRectMake(0, 0, 240, 20);    slider.tag = 100;    slider.minimumValue = 0;    slider.maximumValue = 100;    slider.minimumTrackTintColor = [UIColor greenColor]; //已经滑过的颜色    slider.maximumTrackTintColor = [UIColor blueColor];//滑动条的颜色    slider.value = http://www.mamicode.com/30;    [slider addTarget:self action:@selector(changeVoice:) forControlEvents:UIControlEventValueChanged];    [self.window addSubview:slider];        _imageView = [[UIImageView alloc] init];    _imageView.center = CGPointMake(20, 400);    _imageView.bounds = CGRectMake(0, 0, 20, 20);    _imageView.image = [UIImage imageNamed:@"mid.png"];    [self.window addSubview:_imageView];    //    [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(addValue:) userInfo:slider repeats:YES];        UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];    btn.frame = CGRectMake(0, 0, 20, 20);    [_imageView addSubview:btn];    _imageView.userInteractionEnabled = YES;    [btn addTarget:self action:@selector(voiceChange) forControlEvents:UIControlEventTouchUpInside];    return YES;}//定时器方法，声音自动提高,但这时虽然滑动条的值发生变化，但是并不触发方法- (void)addValue:(NSTimer *)timer{    UISlider *slider = (UISlider *)[timer userInfo];    if (slider.value < 30)    {        slider.value += 0.1;    }}//声音的高低可又图标表示出来- (void)changeVoice:(UISlider *)slider{    if (slider.value =http://www.mamicode.com/= 0)    {        _imageView.image = [UIImage imageNamed:@"none.png"];        return;    }    if (slider.value < 30)    {        _imageView.image = [UIImage imageNamed:@"low.png"];        return;    }    if (slider.value < 60)    {        _imageView.image = [UIImage imageNamed:@"mid.png"];        return;    }    if (slider.value <= 100)    {        _imageView.image = [UIImage imageNamed:@"high.png"];    }}//当声音不为 0 的时候，点击声音图标总是将声音置 0，当再次点击图标的时候，声音恢复- (void)voiceChange{    UISlider *slider = (UISlider *)[self.window viewWithTag:100];    static int count = 0;    count ++;    if (count % 2 != 0)    {        _voiceValue = slider.value;  //记住上次的声音        slider.value = http://www.mamicode.com/0;    }    else    {        if (slider.value != 0) //在回复声音之前已经将声音调节不再为0，则使用递归        {            [self voiceChange];            count = 0;        }        slider.value = _voiceValue;    }}@end