七度&光 2010-05-05 23:25 采纳率: 22.2%
浏览 759
已采纳

如何判断 UIViewController 的视图是否可见

I have a tabbar application, with many views. Is there a way to know if a particular UIViewController is currently visible from within the UIViewController? (looking for a property)

转载于:https://stackoverflow.com/questions/2777438/how-to-tell-if-uiviewcontrollers-view-is-visible

  • 写回答

15条回答 默认 最新

  • 游.程 2010-05-05 23:35
    关注

    The view's window property is non-nil if a view is currently visible, so check the main view in the view controller:

    [EDIT] Invoking the view method causes the view to load (if it is not loaded) which is unnecessary and may be undesirable. It would be better to check first to see if it is already loaded. I've added the call to isViewLoaded to avoid this problem.

    if (viewController.isViewLoaded && viewController.view.window) {
        // viewController is visible
    }
    

    Or if you have a UINavigationController managing the view controllers, you could check its visibleViewController property instead.

    Also, in Swift on iOS 9 (or later):

    if viewController.viewIfLoaded?.window != nil {
        // viewController is visible
    }
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(14条)

报告相同问题?

悬赏问题

  • ¥15 求差集那个函数有问题,有无佬可以解决
  • ¥15 MATLAB动图问题
  • ¥15 【提问】基于Invest的水源涵养
  • ¥20 微信网友居然可以通过vx号找到我绑的手机号
  • ¥15 寻一个支付宝扫码远程授权登录的软件助手app
  • ¥15 解riccati方程组
  • ¥15 display:none;样式在嵌套结构中的已设置了display样式的元素上不起作用?
  • ¥15 使用rabbitMQ 消息队列作为url源进行多线程爬取时,总有几个url没有处理的问题。
  • ¥15 Ubuntu在安装序列比对软件STAR时出现报错如何解决
  • ¥50 树莓派安卓APK系统签名