开关文本字段的最大长度

Question

我有几个文本字段，每个字段的最大字符数不同。我如何将if分支改为枚举并使用switch？

 //if -> switch
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        let newLength = (textField.text ?? "").count + string.count - range.length

        if(textField == textFieldA) {
            return newLength <= 6
        }
        if(textField == textFieldB) {
            return newLength <= 7
        }
        if(textField == textFieldC) {
            return newLength <= 8
        }
        return true
    }

Answer 1

 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        let newLength = (textField.text ?? "").count + string.count - range.length
        switch textField {
           case textFieldA :
               return newLength <= 6
           case textFieldB:
               return newLength <= 7
           case textFieldC:
              return newLength <= 8
           default:
              return true 
        }
}

Answer 2

你使用==将一个字段与多个字段进行比较，所以你应该可以像下面这样做。

switch (textField) {
   case textFieldA:
       return newLength <= 6
   case textFieldB:
       return newLength <= 7
   case textFieldC:
       return newLength <= 8
   default:
       return true
}