Disallow words less than 3 characters

Question

In the Swift code below, the user chooses a word and types it into a text box, now how to disallow the words entered if less than 3 characters in length?

func isReal (word: String) -> Bool {
    //return true
    let checker = UITextChecker()
    let range = NSMakeRange(0, word.utf16.count)
    let misspelledRange = checker.rangeOfMisspelledWord(in: word, range: range, startingAt: 0, wrap: false, language: "en")
    return misspelledRange.location == NSNotFound
}

Answer 1

You can just add an if to check if the word has more than 3 characters:

func isReal (word: String) -> Bool {
    if word.characters.count >= 3 {
        //return true
        let checker = UITextChecker()
        let range = NSMakeRange(0, word.utf16.count)
        let misspelledRange = checker.rangeOfMisspelledWord(in: word, range: range, startingAt: 0, wrap: false, language: "en")
        return misspelledRange.location == NSNotFound
    } else {
        return false
    }
}

This way, if word is shorter than 3 characters, it will return false, otherwise, it will test against the UITextChecker() and then return true or false respectively

EDIT: Alternative using guard:

func isReal (word: String) -> Bool {
    guard word.characters.count >= 3 else {
        return false
    }

    //return true
    let checker = UITextChecker()
    let range = NSMakeRange(0, word.utf16.count)
    let misspelledRange = checker.rangeOfMisspelledWord(in: word, range: range, startingAt: 0, wrap: false, language: "en")
    return misspelledRange.location == NSNotFound
}

If the guard statement is not met (being word.characters.count < 3), the function will automatically return false

Answer 2

You can implement the didEndEditing UItextfieldDelegate method and then check 1) that its a single word and 2) that its longer than 2 characters. At that point you then need to show an error or a red caption label or something.

func textFieldDidEndEditing(_ textField: UITextField, reason: UITextFieldDidEndEditingReason) {
    guard let string = textField.text else {
        return
    }
    let characterSet = CharacterSet(charactersIn: string)
    if characterSet.intersection(CharacterSet.whitespacesAndNewlines).isEmpty != true {
        // we have white space!
    }
    if string.characters.count < 3 {
        // too short
    }
}

Answer 3

You don't need to implement new functions to check an input coming from a UITextField. UITextField has its own functions for that. You should make your ViewController class conform to the UITextFieldDelegate protocol, set it as the delegate for your UITextField, then implement the required delegate method, textFieldDidEndEditing and check the length of the input there.

extension YourViewController: UITextFieldDelegate {
    func textFieldDidEndEditing(_ textField: UITextField) {
        guard let input = textField.text else {return}
        if input.characters.count < 3 {
            //handle error
        }
    }
}

In viewDidLoad of YourViewController:

yourTextField.delegate = self