如何限制Swift文本字段中的数字？

Question

I want the user to fill in the textfield a number from 0 to 60. How can i limit the number chars to 2? How to limit the maximum number to 60? And how to cancel the 'paste' option on the textfield so the user won't be able to paste letters?

Answer 1

I think there are 2 ways you can do that.

Implement the UITextFieldDelegate and implement function

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

    var startString = ""

    if textField.text != nil {
        startString += textField.text!
    }

    startString += string

    var limitNumber = startString.toInt()

    if limitNumber > 60 {
        return false
    } else {
        return true
    }
}

In this Each time check what has been entered to the UITextField so far, convert to Integer and if the new value is higher than 60, return false. (Also show the appropriate error to the user).

I think a much better way would be to provide UIPickerView .

Answer 2

Use textfield's delegate method

Where 10 is Max limit for text field...

      func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
        let newLength = countElements(textField.text) + countElements(string) - range.length
       return newLength <= 10 // Bool
 }

If countElements not work in latest version of s wift use count instead of countElements.

Answer 3

To disable copy and paste:

func canPerformAction(_ action: Selector, withSender sender: AnyObject?) -> Bool
{
    if action == "paste:"
        {return false}
    return super.canPerformAction(action,withSender:sender)
}