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

In swift 4.1 and Xcode 9.4.1

Add UITextFieldDelegate to your class

class YourViewController: UIViewController, UITextFieldDelegate

Then write this code in your viewDidLoad()

mobileNoTF.delegate = self

Write this textfield delegate function

//MARK - UITextField Delegates
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    //For mobile numer validation
    if textField == mobileNoTF {
        let allowedCharacters = CharacterSet(charactersIn:"+0123456789 ")//Here change this characters based on your requirement
        let characterSet = CharacterSet(charactersIn: string)
        return allowedCharacters.isSuperset(of: characterSet)
    }
    return true
}