Check if NSString contains alphanumeric + underscore characters only

Question

I\'ve got a string that needs to be only a-z, 0-9 and _

How do I check if the input is valid? I\'ve tried this but it accepts letter like å,ä,ö,ø etc.

NS         


        

Answer 1

Here's how you can do it in Swift (as an extension of the String class):

extension String {

     func containsValidCharacters() -> Bool {

        var charSet = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_")
        charSet = charSet.invertedSet

        let range = (self as NSString).rangeOfCharacterFromSet(charSet)

        if range.location != NSNotFound {
            return false
        }

        return true
    }
}