How to restrict UITextField to take only numbers in Swift?

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.

Is there any way to restrict user to enter only numeric values in a UITextField?

Solution 1:

Solution for swift 3.0 and above

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let allowedCharacters = CharacterSet.decimalDigits
    let characterSet = CharacterSet(charactersIn: string)
    return allowedCharacters.isSuperset(of: characterSet)
}

Solution 2:

Here is my 2 Cents. (Tested on Swift 2 Only)

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

  let aSet = NSCharacterSet(charactersInString:"0123456789").invertedSet
  let compSepByCharInSet = string.componentsSeparatedByCharactersInSet(aSet)
  let numberFiltered = compSepByCharInSet.joinWithSeparator("")
  return string == numberFiltered

}

This is just a little bit more strict. No decimal point either.

Hope it helps :)

PS: I assumed you looked after the delegate anyway.

Update: Swift 3.0 :

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

    let aSet = NSCharacterSet(charactersIn:"0123456789").inverted
    let compSepByCharInSet = string.components(separatedBy: aSet)
    let numberFiltered = compSepByCharInSet.joined(separator: "")
    return string == numberFiltered
}

Solution 3:

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
}

Solution 4:

Swift 2.0

For only allowing numbers and one "." decimal in uitextfield.

func textField(textField: UITextField,shouldChangeCharactersInRange range: NSRange,replacementString string: String) -> Bool
{
    let newCharacters = NSCharacterSet(charactersInString: string)
    let boolIsNumber = NSCharacterSet.decimalDigitCharacterSet().isSupersetOfSet(newCharacters)
    if boolIsNumber == true {
        return true
    } else {
        if string == "." {
            let countdots = textField.text!.componentsSeparatedByString(".").count - 1
            if countdots == 0 {
                return true
            } else {
                if countdots > 0 && string == "." {
                    return false
                } else {
                    return true
                }
            }
        } else {
            return false
        }
    }
}