UIViewAutoresizingNone：旋转后调整大小

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    ClockVC *clockVC = [[ClockVC alloc]init];
    clockVC.view.frame = CGRectMake(100, 100, clockVC.view.bounds.size.width, clockVC.view.bounds.size.height);

    [self.window addSubview:clockVC.view];
    [self.window makeKeyAndVisible];

    return YES;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.autoresizingMask = UIViewAutoresizingNone;
    self.view.autoresizesSubviews = UIViewAutoresizingNone;
}

/ Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}

-(void) willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration{  
     [UIView animateWithDuration:0.5 
                     animations:^{self.view.alpha = 0;}
     ];
}

-(void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation{ 
    [UIView animateWithDuration:1 
                     animations:^{self.view.alpha = 1;}
     ];
}