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

While most of these solutions will work, be aware that in some localisations a decimals are separated with a "," and not a "."

The cleaner way to do this would be

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let decimalCharacter = NSNumberFormatter().decimalSeparator
    let characterSet = NSMutableCharacterSet.decimalDigitCharacterSet()
    characterSet.addCharactersInString(decimalCharacter)

    return replacementString.rangeOfCharacterFromSet(characterSet.invertedSet) == nil
}