UITextField Custom Clear Button

问题

I'm trying to implement custom clear button in text field using the solution on Custom Clear Button

It doesn't work, it shows default clear button. Any idea why? Following is my code:

class CustomTextField: UITextField {

    override init(frame: CGRect) {
        super.init(frame: frame)

        let clearButton = UIButton(frame: CGRect(x: 0, y: 0, width: 16, height: 16))
        clearButton.setImage(UIImage(named: "Glyph/16x16/Clear")!, for: [])

        self.rightView = clearButton
        clearButton.addTarget(self, action: #selector(clearClicked), for: .touchUpInside)

        self.clearButtonMode = .never
        self.rightViewMode = .whileEditing
    }

    @objc override func clearClicked(sender:UIButton)
    {
        self.text = ""
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}

回答1:

As mentioned already, in your code the clearClicked method should not override as UITextField doesn't have a clearClicked method to override.

Anyway, I updated the code to work when using it with storyboards. Added the awakeFromNib method which calls the initialisation code.

class CustomTextField: UITextField {

    override open func awakeFromNib() {
        super.awakeFromNib()
        self.initialize()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.initialize()
    }

    func initialize() {
        let clearButton = UIButton(frame: CGRect(x: 0, y: 0, width: 16, height: 16))
        clearButton.setImage(UIImage(named: "Glyph/16x16/Clear")!, for: [])

        self.rightView = clearButton
        clearButton.addTarget(self, action: #selector(clearClicked), for: .touchUpInside)

        self.clearButtonMode = .never
        self.rightViewMode = .whileEditing
    }

    @objc func clearClicked(sender:UIButton)
    {
        self.text = ""
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}

来源：https://stackoverflow.com/questions/53675152/uitextfield-custom-clear-button