How to check if a string only contains alphanumeric characters in objective C?

Question

I'm working on a small iphone project and i would need to check if the userName entered only contains alphanumerical characters? (A-Z, a-z, 0-9). How would i go about checking it?

Answer 1

You can use this regular expression library for ObjectiveC. Use the following regex to match:

^[a-zA-Z0-9]*$

Answer 2

If you don't want to bring in a regex library for this one task...

NSString *str = @"aA09";
NSCharacterSet *alphaSet = [NSCharacterSet alphanumericCharacterSet];
BOOL valid = [[str stringByTrimmingCharactersInSet:alphaSet] isEqualToString:@""];

Answer 3

This will work:

@implementation NSString (alphaOnly)

- (BOOL) isAlphaNumeric
   {
    NSCharacterSet *unwantedCharacters = 
       [[NSCharacterSet alphanumericCharacterSet] invertedSet];

    return ([self rangeOfCharacterFromSet:unwantedCharacters].location == NSNotFound) ? YES : NO;
    }

@end

Answer 4

I really like the RegexKit Lite Framework. It uses the ICU regex library, which is already included with OSX and is unicode-safe.

NSString *str = @"testString";
[str isMatchedByRegex:@"^[a-zA-Z0-9]*$"]; // strict ASCII-match
[str isMatchedByRegex:@"^[\p{L}\p{N}]*$"]; // unicode letters and numbers match