How to restrict UITextField to take only numbers in Swift?

Question

I want the user to only enter numeric values in a UITextField. On iPhone we can show the numeric keyboard, but on iPad the user can switch to any keyboard.

Answer 1

This is a more readable version that will do "0-9" plus ".":

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

    let existingTextHasDecimal = textField.text?.rangeOfString(".")
    let replacementTextHasDecimal = string.rangeOfString(".")
    let replacementTextAllCharacters = NSCharacterSet(charactersInString: string)
    let replacementTextOnlyDigits = NSCharacterSet.decimalDigitCharacterSet().isSupersetOfSet(replacementTextAllCharacters)

    if replacementTextHasDecimal != nil && existingTextHasDecimal != nil {
        return false
    }else{
        if replacementTextOnlyDigits == true {
            return true
        }else if replacementTextHasDecimal != nil{
            return true
        }else{
            return false
        }
    }
}