如何在UIView中调用UITextFieldDelegate

Question

当我在视图中单击一个文本字段时，我无法调用UITextField的委托方法。func textFieldShouldReturn(_ textField: UITextField) -> Bool有什么想法吗？

import UIKit
class CustomUIViewScreen: UIView {  
 override func awakeFromNib() {
...
 textField.delegate = self
}

 override func didMoveToWindow() {
    if (self.window != nil) {
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: .UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: .UIKeyboardWillHide, object: nil)
    }
}

@objc func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        if self.frame.origin.y == 0{
            self.frame.origin.y -= keyboardSize.height - 60
        }
        UIView.animate(withDuration: 0.2) {
            self.layoutIfNeeded()
        }
    }
}

 @objc func keyboardWillHide(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        let info = notification.userInfo! as NSDictionary
        let animationDuration = info.object(forKey: UIKeyboardAnimationDurationUserInfoKey)
        UIView.animate(withDuration: animationDuration as! TimeInterval) {
             if self.frame.origin.y != 0 {
                self.frame.origin.y += keyboardSize.height
                self.layoutIfNeeded()
            }
        }
    }
}
}

extension CustomUIViewScreen : UITextFieldDelegate {
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    let nextTag = textField.tag + 1
    let nextResponder = textField.superview?.viewWithTag(nextTag) as UIResponder!

    if (nextResponder != nil) {
        nextResponder?.becomeFirstResponder()
    } else {
        textField.resignFirstResponder()
    }
    return false
}
}

Answer 1

当你点击textfield时，textfield就变成了第一个响应器，下面的委托方法调用：-

func textFieldDidBeginEditing(_ textField: UITextField)

当用户按下return按钮时调用textFieldShouldReturn方法

官方链接：- https://developer.apple.com/documentation/uikit/uitextfielddelegate/1619590-textfielddidbeginediting