iOS横竖屏

首先，确保APP支持屏幕旋转，具体怎么支持，去网上查询一下

然后，在对应的类中进行如下操作

#pragma mark 转屏方法重写
-(UIInterfaceOrientationMask)supportedInterfaceOrientations {    
    return [self.viewControllers.lastObject supportedInterfaceOrientations];
}
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {    
  return [self.viewControllers.lastObject preferredInterfaceOrientationForPresentation];
}
-(BOOL)shouldAutorotate { 
     return self.visibleViewController.shouldAutorotate;
}

最后，在你不想转屏切换的ViewController上重写以下方法：

#pragma mark 转屏方法 不允许转屏
-(UIInterfaceOrientationMask)supportedInterfaceOrientations {  
      return UIInterfaceOrientationMaskPortrait ;
}
- (BOOL)shouldAutorotate{    
  return NO;
}
-(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return UIInterfaceOrientationPortrait;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation {
    return NO;
}

在你想转屏切换的ViewController上可以照这样重写（允许左右横屏以及竖屏）：

- (BOOL)shouldAutorotate {    
   return YES;
}
-(UIInterfaceOrientationMask)supportedInterfaceOrientations {
   return UIInterfaceOrientationMaskAll;
}
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {    
   return UIInterfaceOrientationPortrait;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
   return YES;
}

另外，在ViewController中对于转屏事件可以参见下面的方法进行捕获：

- (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator {
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];    
    [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {
        //计算旋转之后的宽度并赋值
        CGSize screen = [UIScreen mainScreen].bounds.size;
        //界面处理逻辑
        self.lineChartView.frame = CGRectMake(0, 30, screen.width, 200.0);
        //动画播放完成之后
        if(screen.width > screen.height ){
            NSLog(@"横屏");
        }else{
            NSLog(@"竖屏");
        }
    } completion:^(id<UIViewControllerTransitionCoordinatorContext> context) {
        NSLog(@"动画播放完之后处理");    
    }];
}

区分当前屏幕是否为横竖屏的状态，其实通过判断当前屏幕的宽高来决定是不是横屏或者竖屏：

**竖屏时：**宽<高

**横屏时：**宽>高