objective-c - iOS:简单的动画

Question

我想创建一个改变 alpha 值的简单动画:

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:2];
[view1 setAlpha:0.00];
[UIView commitAnimations];

好的，我用这种方式改变了 alpha 值两秒钟，效果很好，但我想要这样的东西: 当 alpha 为 0 时，动画必须再次开始到 alpha = 1 所以动画应该是:alpha 0 -> alpha 1 -> alpha 0 -> alpha 1 -> ...等等，持续时间为两秒。 你能帮帮我吗？

我的完整代码是

-(IBAction){
FirstViewController *firstViewController = [[[FirstViewController alloc] init]autorelease];
[firstViewController.label1 setAlpha:1.00];
[firstViewController.label2 setAlpha:1.00];
view = firstViewController.viewFirst; //this is my view and I copy in other view
[self fadeOut:nil finished:nil context:nil];}

- (void) fadeOut:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {


[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:2];
[UIView  setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(fadeIn:finished:context:) ];
[view setAlpha:0.00];
[UIView commitAnimations];
}

- (void) fadeIn:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:2];
[UIView  setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(fadeOut:finished:context:) ];
[view setAlpha:1.00];
[UIView commitAnimations];
}

Answer 1

在 iOS 4 及更高版本中你可以这样做

   view1.alpha = 1.0;
   [UIView animateWithDuration:2.0
                          delay:0.0
                        options:UIViewAnimationOptionRepeat|UIViewAnimationAutoReverse
                     animations:^{
                        view1.alpha = 0.0;
                     }
                     completion:nil
   ];