iPhone：使用Core Animation过渡视图

Question

On the Mac, the best way for a simple cross-fade transition of views (without any custom keyframe timing) is to do something such as the following excerpt:

[[self animator] replaceSubview:aView with:bView];

Unfortunately the animator property isn't available on the iPhone. What's the best bet of doing this on the iPhone? Is it setting alpha channels on each view? Sample code would be excellent.

Thanks.

Answer 1

The basic way to animate views on the iphone is to use the UIView beginAnimations and commitAnimations calls. They allow you to modify the animatable properties of a view and have those changes animated.

For instance I have a custom view that is hidden and shown using this approach:

- (void) showAView:(CustomAView *)aView
{
  [UIView beginAnimations:nil context:nil];
  [UIView setAnimationDuration:0.5];    
  aView.frame = CGRectMake(0.0f, 110.0f , aView.frame.size.width, aView.frame.size.height);
  [UIView commitAnimations];  
}

- (void) hideAView:(CustomAView *)aView
{
  [UIView beginAnimations:nil context:nil];
  [UIView setAnimationDuration:0.5];  
  aView.frame = CGRectMake(0.0f, self.view.frame.size.height, aView.frame.size.width, aView.frame.size.height);    
  [UIView commitAnimations];
}

By wrapping the frame property change in the UIView beginAnimations/commitAnimations the change has a standard animation applied to it.

You can add additional properties to the animation by using UIView animation class methods eg.

[UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];