1.appdelegate里 

在appdelegate.h 加上 @property(nonatomic,assign)NSInteger allowRotation;

在appdelegate.m加上

- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window

{

if (_allowRotation == 1) {

return UIInterfaceOrientationMaskLandscapeRight;

}

else

{

return (UIInterfaceOrientationMaskPortrait);

}

}

2.在需要强制横屏的页面

2.1 进入页面时写

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

appDelegate.allowRotation = 1;

NSNumber *orientationUnknown = [NSNumber numberWithInt:UIInterfaceOrientationUnknown];

[[UIDevice currentDevice] setValue:orientationUnknown forKey:@"orientation"];

NSNumber *orientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationLandscapeLeft];

[[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];

2.2退出页面时

NSNumber *orientationUnknown = [NSNumber numberWithInt:UIInterfaceOrientationUnknown];

[[UIDevice currentDevice] setValue:orientationUnknown forKey:@"orientation"];

NSNumber *orientationTarget = [NSNumber numberWithInt:UIDeviceOrientationPortrait];

[[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];

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

appDelegate.allowRotation = 0;