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I have a textfield which allows the user to input text and saves this text to a variable and stores it in user defaults. I need the input to be a string therefore I need the textfield to detect the input as being anything but a string. How can I do this?

Eric Aya
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Antonio C
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    What do you not consider a string in a textField? – alexburtnik Nov 16 '16 at 18:35
  • Everything in that text field is a string. You'll need to determine your own rules about what you consider a valid string and compare against those. – Chris Slowik Nov 16 '16 at 18:39
  • I've rephrased the question name to clarify; I need to essentially validate the input to check it is a string (cannot be integers/doubles such as 5 or 5.3) – Antonio C Nov 16 '16 at 18:42
  • You need only alphabetical characters in your textfield ? – Rajat Nov 16 '16 at 18:46
  • yes it needs to be alphabetical @Rajat as the textfield is used to enter a name. BTW the textfielf is in a alert controller – Antonio C Nov 16 '16 at 18:52

4 Answers4

0

You can use this code 

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let characterSet = NSCharacterSet.letters
    return (string.rangeOfCharacter(from: characterSet) != nil)
}

make sure you have set delegate for your textfield properly

Rajat
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  • I know this solution gets used over and over but this is really a terribly inefficient way to verify the characters in the string. – rmaddy Nov 16 '16 at 19:10
  • @rmaddy what is the issue in this solution. I am a noob :) – Rajat Nov 16 '16 at 19:15
  • It's very inefficient to split the entire string into an array and then rejoin all of the array elements back into a string and then compare the two strings just to see if the original string contains valid characters. – rmaddy Nov 16 '16 at 19:17
0

Try this code. Hope it helps you.

func updateSaveButtonState() {
    let text = titleTextField.text ?? ""
    saveButton.isEnabled = !text.isEmpty
}


@IBAction func textEditingChanged(_ sender: UITextField) {
    updateSaveButtonState()
}

@IBAction func returnPressed(_ sender: UITextField) {
    titleTextField.resignFirstResponder()
}
Vitalik Kizlov
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0

try with below code: swift 4.0

func validateOnlyLetters(text: String) -> Bool {
    let characterSet = CharacterSet.decimalDigits
    return (text.rangeOfCharacter(from: characterSet) == nil)
}
Van
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-1

by default, textField.text property is a string. if you don't want the users to enter any numbers, you may refer to this post to vaidate the input before saving into userdefaults.

another post in Swift - How can I check if a string contains letters in Swift?

let letters = NSCharacterSet.letterCharacterSet()

let phrase = "Test case"
let range = phrase.rangeOfCharacterFromSet(letters)

// range will be nil if no letters is found
if let test = range {
    println("letters found")
}
else {
   println("letters not found")
}
Community
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jokerday
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