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

Does this method work for you?

    NSString *string = @"FF";

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

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