获取屏幕旋转事件

我下面介绍两种方法：
1.注册UIApplicationDidChangeStatusBarOrientationNotification通知（举例:在一个viewcontroller类的viewdidload中注册该通知），示例代码如下：
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(statusBarOrientationChange:) name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];
- (void)statusBarOrientationChange:(NSNotification *)notification
{

UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];if (orientation == UIInterfaceOrientationLandscapeRight) // home键靠右{    //}if (    orientation ==UIInterfaceOrientationLandscapeLeft) // home键靠左{    //}if (orientation == UIInterfaceOrientationPortrait){    //}if (orientation == UIInterfaceOrientationPortraitUpsideDown){    //}

}
注意这种方式监听的是StatusBar也就是状态栏的方向，所以这个是跟你的布局有关的，你的布局转了，才会接到这个通知，而不是设备旋转的通知。
当我们关注的东西和布局相关而不是纯粹设备旋转，我们使用上面的代码作为实现方案比较适合。
2.注册UIDeviceOrientationDidChangeNotification通知（举例:我们同样在一个viewcontroller类的viewdidload中注册该通知），示例代码如下：
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientChange:) name:UIDeviceOrientationDidChangeNotification object:nil];
- (void)orientChange:(NSNotification *)noti
{

NSDictionary* ntfDict = [noti userInfo];UIDeviceOrientation  orient = [UIDevice currentDevice].orientation;/* UIDeviceOrientationUnknown, UIDeviceOrientationPortrait,            // Device oriented vertically, home button on the bottom UIDeviceOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top UIDeviceOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right UIDeviceOrientationLandscapeRight,      // Device oriented horizontally, home button on the left UIDeviceOrientationFaceUp,              // Device oriented flat, face up UIDeviceOrientationFaceDown             // Device oriented flat, face down   */       switch (orient)    {        case UIDeviceOrientationPortrait:            break;        case UIDeviceOrientationLandscapeLeft:            break;        case UIDeviceOrientationPortraitUpsideDown:            break;        case UIDeviceOrientationLandscapeRight:            break;        default:            break;    }

}