ios - 翻转 UILabel

Question

我想使用 CABasicAnimation 翻转 UILabel。动画将永远重复，并将在两个不同值之间更改 UILabel 的文本。

- (void)animateLabel
{
     [self.myLabel.layer addAdnimation:[self labelAnimation]  forKey:@"flip"];
}

- (CAAnimation*)labelAnimation
{
     CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
     [animation setRepeatCount:NSIntegerMax];
     [animation setAutoreverses:YES];
     [animation setDuration:2.0];
     [animation setDelegate:self];
     CATransform3D transform = CATransform3DMakeRotation(M_PI_2, 1, 0, 0);
     [animation  setToValue:[NSValue valueWithCATransform3D:transform]];
     return animation;
}

现在，我尝试使用委托(delegate)，但委托(delegate)方法仅在动画首次开始时有效。相反，我需要能够知道标签完成一个周期。有没有一些方便的方法或方式来使用 CALayer 或我必须使用 CADisplay 链接或计时器？在此先感谢您对我的帮助。

Answer 1

要在每个周期都收到通知，请将 RepeatsCount 设置为 1。然后您将在委托(delegate) animationDidStop:finished 中收到通知。然后您只需再次添加相同的动画。

 - (void)animateLabel
 {
     [self.myLabel.layer addAdnimation:[self labelAnimation]  forKey:@"flip"];
 }

 - (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag
{
    [self animateLabel];
    // do other stuff
}

 - (CAAnimation*)labelAnimation
 {
     CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
     [animation setRepeatCount:1];
     [animation setAutoreverses:YES];
     [animation setDuration:2.0];
     [animation setDelegate:self];
      CATransform3D transform = CATransform3DMakeRotation(M_PI_2, 1, 0, 0);
     [animation  setToValue:[NSValue valueWithCATransform3D:transform]];
      return animation;
  }