暂停和恢复AnimateWithDuration动画ios

所以我已经在animateWithDuration方法的帮助下完成了动画，但我需要在app进入后台时停止动画，并在应用程序返回前景时恢复。

有没有办法可以做到这一点： –

我的动画：标签在一定间隔后淡出淡出;

- (void)viewDidLoad { [super viewDidLoad]; [self MyLabelAnimation]; } - (void)MyLabelAnimation { self.myLabel.text = @"Text 1"; [UIView animateWithDuration:0.3 animations:^{ self.myLabel.alpha = 1.0; } completion:^(BOOL finished) { [UIView animateWithDuration:0.3 delay:2.7 options:UIViewAnimationOptionCurveEaseInOut animations:^{ self.myLabel.alpha = 0.0; } completion:^(BOOL finished) { self.myLabel.text = @"Text 2"; [UIView animateWithDuration:0.3 animations:^{ self.myLabel.alpha = 1.0; } completion:^(BOOL finished) { [UIView animateWithDuration:0.3 delay:2.7 options:UIViewAnimationOptionCurveEaseInOut animations:^{ self.myLabel.alpha = 0.0; } completion:^(BOOL finished) { self.myLabel.text = @"Text 3"; [UIView animateWithDuration:0.3 animations:^{ self.myLabel.alpha = 1.0; } completion:^(BOOL finished) { [UIView animateWithDuration:0.3 delay:2.7 options:UIViewAnimationOptionCurveEaseInOut animations:^{ self.myLabel.alpha = 0.0; } completion:^(BOOL finished) { self.myLabel.text = @"Text 4"; [UIView animateWithDuration:0.3 animations:^{ self.myLabel.alpha = 1.0; } completion:^(BOOL finished) { [UIView animateWithDuration:0.0 delay:4.8 options:UIViewAnimationOptionCurveEaseInOut animations:^{ self.myLabel.alpha = 0.0; } completion:^(BOOL finished) { [self MyLabelAnimation]; }]; }]; }]; }]; }]; }]; }]; }]; } 

Answer 1

由于您的动画似乎是一个无限重复的几个较小子动画的序列，您可以随时跟踪动画循环中的位置，在应用变为非活动状态时停止动画，并在应用程序时重新启动动画再次变得活跃。

[编辑：下面添加的示例代码和说明。]

在ViewController.m ：

 @interface ViewController () { int numStages; // 4 * 3 = 12 in our example (4 different text labels, // with 3 substages (alpha ramping up, alpha constant, and alpha ramping down) for each) int globalStage; // varies from 0 to numStages - 1. 0 initially bool animationIsActive; } @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. numStages = 4 * 3; // 4 * 3 = 12 in our example (4 different text labels, // with 3 substages for each text label's appearance (alpha ramping up, alpha constant, and alpha ramping down)) globalStage = 0; // varies from 0 to numStages - 1. 0 initially animationIsActive = NO; self.myLabel.alpha = 0.0; } - (void)animateStage:(int)stage { NSLog(@"animateStage called with argument stage = %d", stage); // make a note in our instance variable of where we need to restart // the animation THE NEXT TIME if it is interrupted or paused // during the current animation: globalStage = (stage + 1) % numStages; self.myLabel.text = [NSString stringWithFormat:@"Text %d", (stage / 3) + 1]; switch (stage % 3) { case 0: // ramp up alpha from 0 to 1 { [UIView animateWithDuration:0.3 animations:^{ self.myLabel.alpha = 1.0; } completion:^(BOOL finished) { // only proceed to next stage if the animation is supposed to be active: if (animationIsActive) { [self animateStage:globalStage]; } }]; } break; case 1: // keep alpha constant at 1 (see comment below) { [UIView animateWithDuration:2.7 animations:^{ self.myLabel.alpha = 0.99999; // changing the 0.99999 to 1.0 causes // this stage to be short-circuited. probably because iOS realizes // that alpha is not really changing in this stage and, being too clever // by half, decides to skip this stage altogether. but 0.99999 is // as close to 1.0 as makes no difference. } completion:^(BOOL finished) { // only proceed to next stage if the animation is supposed to be active: if (animationIsActive) { [self animateStage:globalStage]; } }]; } break; case 2: // ramp down alpha from 1 to 0 { [UIView animateWithDuration:0.3 animations:^{ self.myLabel.alpha = 0.0; } completion:^(BOOL finished) { // only proceed to next stage if the animation is supposed to be active: if (animationIsActive) { [self animateStage:globalStage]; } }]; } break; default: break; } } - (void)viewWillAppear:(BOOL)animated { NSLog(@"viewWillAppear: called"); [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:[UIApplication sharedApplication]]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willResignActive:) name:UIApplicationWillResignActiveNotification object:[UIApplication sharedApplication]]; } - (void)viewDidDisappear:(BOOL)animated { NSLog(@"viewDidDisappear: called"); [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidBecomeActiveNotification object:[UIApplication sharedApplication]]; [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillResignActiveNotification object:[UIApplication sharedApplication]]; } - (void)didBecomeActive:(NSNotification *)notification { NSLog(@"view controller's didBecomeActive: called"); // start the animation is we are stopped if (!animationIsActive) { NSLog(@"animation being (re)started at stage %d", globalStage); [self animateStage:globalStage]; animationIsActive = YES; } } - (void)willResignActive:(NSNotification *)notification { NSLog(@"view controller's willResignActive: called"); // stop the animation NSLog(@"animation being stopped at stage %d", globalStage); animationIsActive = NO; } @end 

1. 我已经分解并将你的动画“夷为平地”为4 * 3 = 12个阶段以便更好地控制。
2. 实例变量globalStage和animationIsActive用于跟踪我们在动画中的位置以及动画是否正在运行。
3. 在viewWillAppear:我们要求在应用变为活动或非活动时收到通知。 当这些事件发生时，我们的方法didBecomeActive:或willResignActive:被调用。 这两种方法是我们（重新）启动和停止动画的地方。
4. 不要忘记在viewDidDisappear:取消注册两个UIApplication通知viewDidDisappear: 。