Textfield shouldChangeCharactersIn for password field clear

问题

I am using MVVM Structure and when textfield value changed update the view model.
Everything working fine except password field

Here is code

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if let text = textField.text,
        let range = Range.init(range, in: text) {

        let newText = text.replacingCharacters(in: range, with: string)

        if textField == txtOldPassword {
            changePasswordViewModel.updateOldPassword(string: newText)
        } else if textField == txtNewPassword {
            changePasswordViewModel.updateNewPassword(string: newText)
        } else if textField == txtConfirmPassword {
            changePasswordViewModel.updateConfirmPassword(string: newText)
        }  
    }

    return true
}

as password filed cleared when backspace (or delete button) tapped from keyboard newText is returning previously set value not empty string.

issue: when password field is clear still newText has string

When I try to see range returned by function it not looks valid

po range expression produced error: error: Execution was interrupted, reason: EXC_BAD_ACCESS (code=10, address=0x107a2b000). The process has been returned to the state before expression evaluation.

I know I can do it textField.clearsOnBeginEditing = false; but I want it to be clear as default functionality.

Please help me Thanks in advance

回答1:

textField:shouldChangeCharactersInRange:replacementString: is called before text on textField is changed so it's not right place to do these works.

We have another way to check text changed and I think it can resolve your problem.

txtOldPassword.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
txtNewPassword.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
txtConfirmPassword.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)

@objc func textFieldDidChange(textField: UITextField) -> Void {
  if let text = textField.text {
    if textField == txtOldPassword {
      changePasswordViewModel.updateOldPassword(string: text)
    } else if textField == txtNewPassword {
      changePasswordViewModel.updateNewPassword(string: text)
    } else if textField == txtConfirmPassword {
      changePasswordViewModel.updateConfirmPassword(string: text)
    }
  }
}

textFieldDidChange(textField:) will be called after text is changed.

来源：https://stackoverflow.com/questions/50266486/textfield-shouldchangecharactersin-for-password-field-clear