UIViewController 之间的动画切换
两个UIView之间的翻转可以用动画效果翻转(上下，左右)
?? ?UIViewController之间的切换除了UINavigationController里面的pushViewController和 popViewController与UITalbarController在viewControllers之间的切换外， 我们还可以在其他地方自由的进行ViewController切换：
MyViewController *_myViewController = [[MyViewController alloc] init];
_myViewController.modalTransitionStyle =?UIModalTransitionStyleFlipHorizontal;
[self?presentModalViewController: _myViewController Animated: YES];
[_myViewController release];
?
有四种切换形式（modalTransitionStyle）：????
?UIModalTransitionStyleFlipHorizontal??
?UIModalTransitionStyleCoverVertical (default) ??
?UIModalTransitionStyleCrossDissolve?? ?
?UIModalTransitionStylePartialCurl
退回方法：[self?dismissModalViewControllerAnimated:YES];
与此对应的是播放视频时：
?[self?presentMediaPlayerViewController:moviePlayer Animated:YES];
?[self?dismissMediaPlayerViewControllerAnimated:YES];
