ios - Swift 键盘避免 View 无法按预期工作

Question

在上面的 GIF 中，loginMenu 应该是一个键盘避免 View 。它永远不会被键盘覆盖。当开始编辑这些文本字段中的任何一个时，loginMenu 确实会“向上推”，但是，在编辑后，loginMenu 会返回到其原始位置。这里有什么问题？这是我的代码:

import UIKit;

class LoginScreenViewController: UIViewController {
    @IBOutlet weak var loginMenu: UIView!;

    override func viewDidLoad() {
        super.viewDidLoad();

        NotificationCenter.default.addObserver(
            self,
            selector: #selector(keyboardWillChange(notification:)),
            name: .UIKeyboardWillChangeFrame,
            object: nil
        );
    }

    override func viewWillDisappear(_ animated: Bool) {
        NotificationCenter.default.removeObserver(self);
    }

    @objc func keyboardWillChange(notification: Notification) {
        let keyboardHeight = (notification.userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue.height;
        UIView.animate(withDuration: 0.5, animations: { () -> Void in
            self.loginMenu.frame.origin.y = UIScreen.main.bounds.height - keyboardHeight - self.loginMenu.frame.height;
        });
    }
}

Answer 1

这里是解决方案，创建loginMenu View 的底部布局约束引用

@IBOutlet weak var bottomConstraint: NSLayoutConstraint!
@IBOutlet weak var loginMenu: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardNotification), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardNotification), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    }

    override func viewWillDisappear(_ animated: Bool) {
        NotificationCenter.default.removeObserver(self)
    }

    @objc func handleKeyboardNotification(_ notification: Notification) {

    if let userInfo = notification.userInfo {

        let keyboardFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as AnyObject).cgRectValue

        let isKeyboardShowing = notification.name == NSNotification.Name.UIKeyboardWillShow

        bottomConstraint?.constant = isKeyboardShowing ? -keyboardFrame!.height : 0

        UIView.animate(withDuration: 0.5, animations: { () -> Void in
            self.view.layoutIfNeeded()
        })
    }
}

Demo Example