ios - UITextField 的不同过滤器(实例变量)

Question

我想使用 UITextField 的实例变量并为每个 UITextField 实例设置不同的过滤器。我该怎么做？

class ViewController: UITextFieldDelegate {

...

func ... {
   ...
   textField1.delegate = self
   textField2.delegate = self
}

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    // but the problem that textField1, textField2 should be class variables, not instance variables...

    if textField1 == textField {

        let aSet = NSCharacterSet(charactersIn:"0123456789").inverted
        let compSepByCharInSet = string.components(separatedBy: aSet)
        let numberFiltered = compSepByCharInSet.joined(separator: "")
        return string == numberFiltered
    } else if textField2 == textField { ... }

...

}

更新

在 Android 中我可以做这样的事情

editText1.setFilters(new InputFilter[] { new InputFilter() {
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    // if...
    return ...
   };
 });

editText2.setFilters(new InputFilter[] { new InputFilter() {
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
    // if...
    return ...
   };
 });

editText1 和 editText2 都是实例变量

Answer 1

您可以通过创建单独的 UITextFieldDelegate 子类并将它们分配为委托(delegate)来执行类似的操作。

基本方法:

class AlphaOnlyTextFieldDelegate: NSObject, UITextFieldDelegate {

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        print("Alpha:", string)
        // do what you want - such as allowing only Alpha chars
        return true
    }

}

class NumbersOnlyTextFieldDelegate: NSObject, UITextFieldDelegate {

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        print("Numbers:", string)
        // do what you want - such as allowing only Numeric chars
        return true
    }

}

class TheChildVC: UIViewController {

    @IBOutlet var tfAlpha: UITextField!
    @IBOutlet var tfNumbers: UITextField!

    var alphaDelegate = AlphaOnlyTextFieldDelegate()
    var numbersDelegate = NumbersOnlyTextFieldDelegate()

    override func viewDidLoad() {
        super.viewDidLoad()

        tfAlpha.delegate = alphaDelegate
        tfNumbers.delegate = numbersDelegate

    }

}

编辑:

上述的一个优点是您可以将“预先设计的”委托(delegate)分配给任何文本字段。

另一种方法是子类 UITextField，其委托(delegate)函数作为其自身的一部分:

class AlphaTextField: UITextField, UITextFieldDelegate {

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

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

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        print("Alpha Class:", string)
        // do what you want - such as allowing only Alpha chars
        return true
    }

}