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

Extend your view controller like this:

class MyViewController: UIViewController, UITextFieldDelegate

In the viewDidLoad function extend to your text field like this:

myTextField.delegate = self

And then use the following function:

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let isNumber = CharacterSet.decimalDigits.isSuperset(of: CharacterSet(charactersIn: string))
    let withDecimal = (
        string == NumberFormatter().decimalSeparator &&
        textField.text?.contains(string) == false
    )
    return isNumber || withDecimal
}

This will now make sure the user can enter only decimal digits.

Swift 4 + Accepts Number only and accepts one separator

Answer 2

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
}

Answer 3

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
}

Answer 4

Set KeyboardType Property :- Number Pad TextField Delegate please write below code

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

    if textField.text?.count == 0 && string == "0" {
        return false
    }
    return string == string.filter("0123456789".contains)
}

Number should not start from 0 and entered number +ve.

Answer 5

As if there aren't enough answers, here's mine. I think every example allowed for decimal separators is flawed in either localization, backspaces, or copy/paste.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    if string.isEmpty {return true} //allow for backspace

    let decimalSeparator = NSNumberFormatter().decimalSeparator ?? "."
    let validChars = NSMutableCharacterSet(charactersInString: decimalSeparator)
    validChars.formUnionWithCharacterSet(NSCharacterSet.decimalDigitCharacterSet())

    if validChars.isSupersetOfSet(NSCharacterSet(charactersInString: string)){
        switch string.componentsSeparatedByString(decimalSeparator).count-1 {
        case 0: //no decimals
            return true

        case 1: //if adding decimal, only allow if no existing decimal
            if let existingText = textField.text{
                return existingText.componentsSeparatedByString(decimalSeparator).count <= 1
            }
            else {return true}

        default: //invalid decimals
            return false
        }
    }

    return false
}

Answer 6

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
}