Question

我有一个自定义UIViewController，在其中实现了一个自定义用户输入对话框。当用户点击UITextField时，出现键盘，并且消息窗口向上移动。

该代码首次正常运行。但是，当我关闭包含自定义消息对话框的视图控制器，并再次对其进行设置时，实现用户输入对话框的UIView似乎无法正确移动（缺少我输入的偏移量）

首先，我实现了对UIViewController的扩展（通过使用this post和this one中的代码示例）

extension UIViewController {

    // forHeight is the height of the message view that will be shifted up/down
    func setNotificationCentreForKeyboardEvents(forHeight:CGFloat) {
        // Set the selector functions for NSNotification.Name.UIKeyboardWillShow/Hide
        NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name: Notification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide), name: Notification.Name.UIKeyboardWillHide, object: nil)
    }

    // In order for this function to work, the "tag" the message view that is goingto be moved up
    // needs to be set to 55
    @objc func keyboardWillShow(notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue,
            let messageView = self.view.viewWithTag(55) {

            // create a rect with the dimensions of the keyboard
            let aRectY:CGFloat = self.view.frame.height - keyboardSize.height
            let aRect = CGRect(x: 0, y: aRectY, width: self.view.frame.size.width, height: keyboardSize.height)

            // find the inersection of this rect with the message view
            let intersection = aRect.intersection(messageView.frame)

            if self.view.frame.origin.y == 0 {
                self.view.frame.origin.y -= intersection.size.height+20
            }
        }
    }

    // In order for this function to work, the "tag" the message view that is goingto be moved down
    // needs to be set to 55
    @objc func keyboardWillHide(notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue,
            let messageView = self.view.viewWithTag(55) {

            // create a rect with the dimensions of the keyboard
            let aRectY:CGFloat = self.view.frame.height - keyboardSize.height
            let aRect = CGRect(x: 0, y: aRectY, width: self.view.frame.size.width, height: keyboardSize.height)

            // find the inersection of this rect with the message view
            let intersection = aRect.intersection(messageView.frame)

            if self.view.frame.origin.y == 0 {
                self.view.frame.origin.y += intersection.size.height - 20
            }
        }
    }
}

在包含用户输入对话框的自定义UIViewController中，我有

override func viewDidLoad() {
...

    messageView.tag = 55
    setNotificationCentreForKeyboardEvents(forHeight: messageView.frame.size.height)
...
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    NotificationCenter.default.removeObserver(self)
}

并且，对包含自定义用户输入对话框的视图执行segue的viewController具有

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if (segue.identifier == showItemSegueName) {
        let destination = segue.destination as! ItemsViewController
        destination.listName = selectedListName
    } else if (segue.identifier == "addListSegue") {
        let newController: AddListingDialogViewController = segue.destination as! AddListingDialogViewController
        newController.modalPresentationStyle = .overFullScreen
    }
}

这是它的行为

我在这里想念什么？为什么在第一次触发segue后代码无法按预期工作？

谢谢

移动UIView以避免被键盘覆盖

0 个答案: