限制设置包中文本字段中的字符数

Question

I am new to Xcode / Swift and have been following examples online to add a settings bundle to my app.

What I am struggling with is how to limit the number of characters a user can enter in a settings text field. The root.plist does not seem to have this as an option and this answer seems to be for a textfield within the app rather than one that is changed in settings.

Please can someone point me in the right direction.

Answer 1

Unfortunately this cannot be done for text entered in the settings bundle. You do not have control over this.

You could parse the result within your app when loaded from UserDefaults and make changes then if needed, possibly with an alert to the user.

The settings root.plist will let you add footer text below controls, so you could at least provide information for user letting them know the maximum length.

An alternative option would be to use a custom settings page within your app, with a UITextField . Then use the UITextFieldDelegate method shouldChangeCharactersIn to control text entry length.

Answer 2

set delegate of your TextField to self and conform your ViewController to UITextFieldDelegate

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        guard let textFieldText = textField.text,
            let rangeOfTextToReplace = Range(range, in: textFieldText) else {
                return false
        }
        let substringToReplace = textFieldText[rangeOfTextToReplace]
        let count = textFieldText.count - substringToReplace.count + string.count
        return count <= 10  //number of characters 
    }

Answer 3

You need to set the delegate of textField and then you have to implement the method mentioned as below

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
   let text = (textField.text as NSString?)?.replacingCharacters(in: range, with: string) ?? ""
   return text.count <= 10 // your count 
}