swift - Toast UILabel 出现在屏幕外，尽管我正确设置了 y

Question

我在 ViewController 上有一个 Toast 扩展，它继承了 class ViewControllerList: UITableViewController, UIPopoverPresentationControllerDelegate { 一切都很好，除了当我这样做的时候

extension UIViewController {

  func showToast(message : String) {
      let height = UIScreen.main.bounds.height
      let toastLabel = UILabel(frame: CGRect(x: self.view.frame.size.width/2 - 75, y:  height-100, width: 150, height: 35))
      toastLabel.backgroundColor = UIColor.black.withAlphaComponent(0.6)
      toastLabel.textColor = UIColor.white
      toastLabel.textAlignment = .center;
      toastLabel.font = UIFont(name: "Montserrat-Light", size: 12.0)
      toastLabel.text = message
      toastLabel.alpha = 1.0
      toastLabel.layer.cornerRadius = 10;
      toastLabel.clipsToBounds  =  true
      self.view.addSubview(toastLabel)
      UIView.animate(withDuration: 4.0, delay: 0.1, options: .curveEaseOut, animations: {
          toastLabel.alpha = 0.0
      }, completion: {(isCompleted) in
          toastLabel.removeFromSuperview()
      })
   }
}

toast 总是出现在屏幕外 .. 在一个长的 uitableview 中 .. 无论我如何设置 y 它总是根据文档来思考.. 我已经调试了它并且 y= 676 但它似乎位于距离最后一个单元格内的 tableView 底部约 900 ...100 处

这是为什么，我该如何解决？

请不要记下来 - 尝试给出答案

Answer 1

不要添加到 self.view，而是将 toast 标签添加为窗口的 subview :

extension UIViewController {

  func showToast(message : String) {
      let window = (UIApplication.shared.delegate as! AppDelegate).window
      let height = window.bounds.height
      let toastLabel = UILabel(frame: CGRect(x: window.bounds.width/2 - 75, y:  height-100, width: 150, height: 35))
      toastLabel.backgroundColor = UIColor.black.withAlphaComponent(0.6)
      toastLabel.textColor = UIColor.white
      toastLabel.textAlignment = .center;
      toastLabel.font = UIFont(name: "Montserrat-Light", size: 12.0)
      toastLabel.text = message
      toastLabel.alpha = 1.0
      toastLabel.layer.cornerRadius = 10;
      toastLabel.clipsToBounds  =  true

      // notice the change here
      window.addSubview(toastLabel)
      UIView.animate(withDuration: 4.0, delay: 0.1, options: .curveEaseOut, animations: {
          toastLabel.alpha = 0.0
      }, completion: {(isCompleted) in
          toastLabel.removeFromSuperview()
      })
   }
}

这避免了当父 View 是 ScrollView 时你必须处理的问题。