//开启动画
[UIView beginAnimations:@"View Flip" context:nil];
//设置动画时间
[UIView setAnimationDuration:1];
[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
//判断当前显示的UIView是不是yellowViewController.
//如果显示的不是yellowViewController，它的view‘s superview就是nil.
if([[self.yellowViewController view] superview] == nil){
//判断yellowViewController有没有创建。
if(self.yellowViewController == nil){//创建yellowViewController，initWithNibName根据nib文件名称创instance。}
YellowViewController *_yellowViewController = [[YellowViewController alloc]
initWithNibName:@"YellowView" bundle:nil];
self.yellowViewController = _yellowViewController;
[_yellowViewController release];
//设置动画转换效果为flipFromRight.
[UIView setAnimationTransition:
UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];
[self.blueViewController viewWillAppear:YES];
[self.yellowViewController viewWillDisappear:YES];
[self.blueViewController.view removeFromSuperview];
[self.view insertSubview:self.yellowViewController.view atIndex:0];
[self.blueViewController viewWillDisappear:YES];
[self.yellowViewController viewWillAppear:YES];
}else{
if(self.blueViewController == nil){
BlueViewController *_blueViewController = [[BlueViewController alloc]
initWithNibName:@"BlueView" bundle:nil];
self.blueViewController = _blueViewController;
[_blueViewController release];
}
[UIView setAnimationTransition:
UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES];
[self.blueViewController viewWillDisappear:YES];
[self.yellowViewController viewWillAppear:YES];
[self.yellowViewController.view removeFromSuperview];
[self.view insertSubview:self.blueViewController.view atIndex:0];
[self.blueViewController viewWillAppear:YES];
[self.yellowViewController viewWillDisappear:YES];
}
[UIView commitAnimations];
iPhone application中，view的层级关系
|---- window
|---- subView (RootViewController ‘s View)
|----OtherViewController ‘s View
在window出现后，调用delegate的applicationDidFinishLaunching 方法，通过方法[window addSubView:rootViewController.view];来显示RootViewController的UIView给用户。所以，这 个 UIView就是一个顶层的显示界面。然后通过rootViewController.view的insertSubView将 yellowViewController.view显示在window中。
原文：http://www.cnblogs.com/allanliu/p/4203318.html