How to limit length and special characters of UItextField?

Question

I'm able to limit the length using the code below, but I can't seem to find a way to also limit special characters.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let newLength = count(textField.text.utf16) + count(string.utf16) - range.length
if (textField.placeholder == "USERNAME")
{
    //Also limit special characters here
    return newLength <= 15 // Bool
}

characters I want allowed:

ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.

I tried following this link but its in objective C and I'm having trouble merging it with my current 15 character limit code above

score 3 · Accepted Answer · answered Aug 06 '15 at 13:05

3

Alternative to regex, you can first get all the allowed characters into a set:

 var charactesAllowed = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_."
 var charactersSet = [Character](charactesAllowed)

then try to see if the most recently typed charactes is in this array

var newCharacter = //whatever the character is, ex: "A"
if(contains(charactersSet, newCharacter))
{
    println("Allowed")
    // Add it into the label text
}

answered Aug 06 '15 at 13:05

dorian

801
5
11

I used this as a reference and it led me to what I was looking for. I had to create an extension for contains – SlopTonio Aug 06 '15 at 14:24

score -3 · Answer 2 · edited Sep 01 '17 at 12:03

let  ACCEPTABLE_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"


if textField == textFieldNumber{
            let characterSet = CharacterSet.init(charactersIn: ACCEPTABLE_CHARACTERS).inverted
            maxLength = 11
            let currentString: NSString = textField.text! as NSString
            let newString: NSString =
                currentString.replacingCharacters(in: range, with: string) as NSString
            let filter = string.components(separatedBy: characterSet).joined(separator:"")
            return ((string == filter) && newString.length <= maxLength!)
        }

How to limit length and special characters of UItextField?

2 Answers2