swift - 从父 View 中删除 View

Question

当 View 消失时，我从 super View 中删除了这个 Collection View ，因为内存问题，但我想在 View 出现时将其添加回来，我只想将它添加回来!或者还有另一种方法吗？谢谢。

  override func viewWillDisappear(_ animated: Bool) {
       super.viewWillDisappear(animated)
       let subViews = self.view.subviews
       for subview in subViews{
           if subview.tag == 1 {
              subview.removeFromSuperview()
            }
        }        
    }

更新

 var savedView: UIView?

 override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    let subViews = self.view.subviews
    for subview in subViews{
        if subview.tag == 1 {
            savedView = subview
            subview.removeFromSuperview()
        }
    }
}




override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    if let subview = savedView {
        view.addSubview(subview)
        savedView = nil
    }
}

但它不会将其添加回来。

Answer 1

在您的 View Controller 中创建一个可选属性。在您的 viewDidDisappear 方法中将找到的 subview 分配给此可选属性。然后在 viewWillAppear 方法中，您可以检查是否设置了可选属性。如果已设置，则将其添加回 subview 。

添加此属性:

var savedView: UIView?

然后在 viewDidDisappear 中执行此操作:

override func viewDidDisappear(_ animated: Bool) {
   super.viewDidDisappear(animated)
   // This assumes there is no other deep subview with a tag of 1
   // If this isn't true, use your current for-loop to find the subview
   if let subview = subviews.viewWithTag(1) {
       savedView = subview
       subview.removeFromSuperview
   }
}

然后在 viewWillAppear 中执行此操作:

override func viewWillAppear(_ animated: Bool) {
   super.viewWillAppear(animated)
   if let subview = savedView {
       addSubview(savedView)
       savedView = nil
   }
}