iOS屏幕旋转的bug

控制屏幕旋转的方法如果不好使，那就创建一个navigationController的类目；

实现三个方法：

-(BOOL)shouldAutorotate {

    return [[self.viewControllers lastObject] shouldAutorotate];

}

-(NSUInteger)supportedInterfaceOrientations {

    return [[self.viewControllers lastObject] supportedInterfaceOrientations];

}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {

    return [[self.viewControllers lastObject] preferredInterfaceOrientationForPresentation];

}

当然原来的方法也要保留，不然也不好使。