Validate NSString for Hexadecimal value

Question

I'm working on a custom NSFormatter. I need to verify user input step by step... i thought to check by isPartialStringValid: if the string contains only permitted chars "0123456789ABCDEF". How can i verify this condition ? is there a way with NSString function to check if a string contain only some chars ?

Answer 1

Swift 5

extension String {
    var isHexNumber: Bool {
        filter(\.isHexDigit).count == count
    }
}

print("text1".isHexNumber) // false
print("aa32".isHexNumber) // true
print("AD1".isHexNumber) // true

Answer 2

Does this method work for you?

    NSString *string = @"FF";

    NSCharacterSet *chars = [[NSCharacterSet 
        characterSetWithCharactersInString:@"0123456789ABCDEF"] invertedSet];

    BOOL isValid = (NSNotFound == [string rangeOfCharacterFromSet:chars].location);

Answer 3

You can create a custom NSCharacterSet that contains the permitted characters (+ characterSetWithCharactersInString:) and then test the string against it with rangeOfCharacterFromSet:. If the returned range is equal to the entire range of the string, you have a match.

Another option would be matching with NSRegularExpression.

Sample code Swift:

func isValidHexNumber() -> Bool {
    guard isEmpty == false else { return false }
    let chars = CharacterSet(charactersIn: "0123456789ABCDEF").inverted
    return uppercased().rangeOfCharacter(from: chars) == nil
}

Answer 4

In swift 2.1 you can extends String in this way:

extension String {

  func isValidHexNumber() -> Bool {
    let chars = NSCharacterSet(charactersInString: "0123456789ABCDEF").invertedSet
    guard self.uppercaseString.rangeOfCharacterFromSet(chars) != nil else {
        return false
    }
    return true
  }

}