Question 67466 in IOS Swift Question posted in
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How to allow to type only one sentence (word or chars) in TextField? Swift 5 – Ios swift

Hello everyone!) Need some help!)

How can I allow the user to enter only one sentence (word or characters) in a TextField with some rules?)

The user must enter only this word:

Qwerty

Then text field must shows automatically hyphen:

Qwerty-

And after that the user can type in text field only this digits:

12345

Expected result must be only this:

Qwerty-12345

The order of entering each letter or number is very important!)

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let text = onlyCharTextField.text else { return true }
    
    if textField == onlyCharTextField {
        
        let allowedCharacters = "Q-w-e-r-t-y "
        let allowedCharacterSet = CharacterSet(charactersIn: allowedCharacters)
        
        let allowedDigits = "1-2-3-4-5"
        let allowedDigitSet = CharacterSet(charactersIn: allowedDigits)
        
        if text == "Qwerty" {
            onlyCharTextField.text = "Qwerty" + "-"
        }

        let typedCharacterSet = CharacterSet(charactersIn: string)
        
        let alphabet = allowedCharacterSet.isSuperset(of: typedCharacterSet) || allowedDigitSet.isSuperset(of: typedCharacterSet)
        return alphabet
        
        
    } else {
        return false
    }
}

I’m confused..(( Do you have any ideas how to implement this?)
Thanks for every answer!)

Tags:

2

Answers


  1. 0

    It’s not that complicated. You can use the "first compute what the new text would be" pattern, and then check if "Qwerty-12345" starts with that text. This is because if the text is entered in the correct order, then the text is always a part (or the entirety) of the beginning of "Qwerty-12345":

    Q
Qw
Qwe
Qwer
Qwert
Qwerty-
Qwerty-1
Qwerty-12
Qwerty-123
Qwerty-1234
Qwerty-12345

    A special case is when the text is Qwerty. This is when you don’t allow the keyboard to change the text, and instead change it programmatically to Qwerty-.

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let text = (textField.text ?? "") as NSString
    let newText = text.replacingCharacters(in: range, with: string)
    if newText == "Qwerty" {
        textField.text = "Qwerty-"
        return false
    }
    return "Qwerty-12345".starts(with: newText)
}

    Note that this still allows the user to delete what they have already entered, but only from the end, and enter Qwerty-12345 from the deleted point. If you want to disallow that, you can check if the replacementString parameter is empty, which is indicative of a deletion:

    if string.isEmpty {
    return false
}

    This doesn’t disable pasting. If you want that, see How to disable pasting in a TextField in Swift?

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  2. 0 
        func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        
        let expectedText = "Qwerty-12345" //Text u want user to enter
        let halfText = "Qwerty" //special case where u enter an additional -
        
        let enteredText = "(textField.text ?? "")(string)" //get the text user has entered
        
        if  enteredText == expectedText.prefix(enteredText.count){ //check if the user entered text matches to the the first part of your string
            // if it matches change the text of the text field
            if enteredText == halfText{
                textField.text = "(enteredText)-" //special case where u add an -
            }
            else{
                textField.text = enteredText
            }
        }
        return false
    }
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