app锁定屏幕方向，某一个界面支持屏幕旋转~

AppDelegate.h 加

@property (nonatomic, assign) BOOL allowRotation;

Appdelegate.m加

-(NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
　　if (self.allowRotation) {
　　　　return UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight;
　　}
　　return UIInterfaceOrientationMaskPortrait;
}
- (NSUInteger)supportedInterfaceOrientations
{
　　return UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight;
}
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
　　return UIInterfaceOrientationPortrait;
}

之后在需要支持屏幕旋转的界面的特定位置上添加代码：

• 打开屏幕旋转：

　　AppDelegate  *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
　　delegate.allowRotation = YES;

• 关闭屏幕旋转：

　　AppDelegate  *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
　　delegate.allowRotation = NO;