ios - 如何在swift中使用Google Material MDCOutlinedTextField从文本字段中删除占位符文本？

Question

这是我编写的代码，但是当用户在文本字段中但没有文本时，文本字段中仍然出现占位符，并且还显示在浮动标签中，当我在此文本字段中时，我只想删除

func setupGoogleMaterialTextFields(textFields: [MDCOutlinedTextField]) {
    let containerShceme = MDCContainerScheme()
    let colorScheme = MDCSemanticColorScheme()
    colorScheme.primaryColor = UIColor.white
    colorScheme.onSurfaceColor = UIColor.white
    containerShceme.colorScheme = colorScheme
    for textField in textFields {
        textField.label.text = textField.placeholder 
        textField.font = UIFont.myMediumSystemFont(ofSize: 18)

        textField.attributedPlaceholder = NSAttributedString(string: textField.placeholder ?? "",
                                                             attributes: [NSAttributedString.Key.foregroundColor: UIColor.white,
                                                                          NSAttributedString.Key.font: UIFont.myMediumSystemFont(ofSize: 16)])
        textField.containerRadius = 8
        textField.sizeToFit()
        textField.applyTheme(withScheme: containerShceme)
    }
}

Answer 1

我已经像这样将委托分配给 textField 。

func setupGoogleMaterialTextFields(textFields: [MDCOutlinedTextField]) {
    let containerShceme = MDCContainerScheme()
    let colorScheme = MDCSemanticColorScheme()
    colorScheme.primaryColor = UIColor.white
    colorScheme.onSurfaceColor = UIColor.white
    containerShceme.colorScheme = colorScheme
    for textField in textFields {
        textField.label.text = textField.placeholder 
        textField.font = UIFont.myMediumSystemFont(ofSize: 18)

        textField.attributedPlaceholder = NSAttributedString(string: textField.placeholder ?? "",
                                                             attributes: [NSAttributedString.Key.foregroundColor: UIColor.white,
                                                                          NSAttributedString.Key.font: UIFont.myMediumSystemFont(ofSize: 16)])
        textField.containerRadius = 8
        textField.sizeToFit()
        textField.applyTheme(withScheme: containerShceme)
        textField.delegate = self
    }
}

分配委托后执行此操作。

    extension youClassName: UITextFieldDelegate {

    func textFieldDidBeginEditing(_ textField: UITextField) {
        if textField.text?.isEmpty ?? false {
            textField.placeholder = nil
        }
    }
}