iOS获取屏幕最上层的ViewController

实际开发中，时长需要获取屏幕最上层的ViewController，以下代码是对实现此需求的简单代码封装。

PS:以下代码被封装为UIApplication类的分类

<pre>
`
//获取rootViewController

• (UIViewController )rootViewController{
  UIWindow window = [UIApplication sharedApplication].keyWindow;
  return window.rootViewController;
  }
  `
  </pre>

<pre>
`
//获取Window当前显示的ViewController

• (UIViewController)currentViewController{
  UIViewController vc = [UIApplication rootViewController];

  while (1) {
  if ([vc isKindOfClass:[UITabBarController class]]) {
  vc = ((UITabBarController*)vc).selectedViewController;
  }

    if ([vc isKindOfClass:[UINavigationController class]]) {
        vc = ((UINavigationController*)vc).visibleViewController;
    }
    
    if (vc.presentedViewController) {
        vc = vc.presentedViewController;
    }else{
        break;
    }
  

  }

  return vc;
  }

`
</pre>