iOS设备有Portrait (正向)，Upside down (颠倒)，Landscape Left （向左侧翻转）和 Landscape Right (向右侧翻转)四个方向.可以在AppDelegate可以根据设备来设置不同的方向：

- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
    return UIInterfaceOrientationMaskPortrait;
}

设备方向可以通过UIInterfaceOrientationMask枚举来设置:

typedef NS_OPTIONS(NSUInteger, UIInterfaceOrientationMask) {
    UIInterfaceOrientationMaskPortrait = (1 << UIInterfaceOrientationPortrait),
    UIInterfaceOrientationMaskLandscapeLeft = (1 << UIInterfaceOrientationLandscapeLeft),
    UIInterfaceOrientationMaskLandscapeRight = (1 << UIInterfaceOrientationLandscapeRight),
    UIInterfaceOrientationMaskPortraitUpsideDown = (1 << UIInterfaceOrientationPortraitUpsideDown),
    UIInterfaceOrientationMaskLandscape = (UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight),
    UIInterfaceOrientationMaskAll = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight | UIInterfaceOrientationMaskPortraitUpsideDown),
    UIInterfaceOrientationMaskAllButUpsideDown = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight),
} __TVOS_PROHIBITED;

如果项目中有些页面要求特定的方向旋转，可以在ViewController中设置:

- (BOOL)shouldAutorotate {
    return YES;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    return UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationLandscapeRight;
}

默认方向设置:

-(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return UIInterfaceOrientationPortrait;
}

旋转通知:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceOrientationChange:) name:UIDeviceOrientationDidChangeNotification object:nil];

- (void)deviceOrientationChange:(NSNotification *)notification {
    
    UIDeviceOrientation  orient = [UIDevice currentDevice].orientation;
    
    switch (orient) {
        case UIDeviceOrientationPortrait:
            
            break;
        case UIDeviceOrientationLandscapeLeft:
            
            break;
        case UIDeviceOrientationPortraitUpsideDown:
            
            break;
        case UIDeviceOrientationLandscapeRight:
            
            break;
            
        default:
            break;
    }
}

状态栏变更通知:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceOrientationChange:) name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];

- (void)statusBarOrientationChange:(NSNotification *)notification{
    
    UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
    
    if (orientation == UIInterfaceOrientationLandscapeRight) {
        
    }
    
    if (orientation ==UIInterfaceOrientationLandscapeLeft) {

    }
    
     if (orientation == UIInterfaceOrientationPortrait){
         
     }
    
    if (orientation == UIInterfaceOrientationPortraitUpsideDown){

    }
}