[SOLVED] Regex to validate Uniform Type Identifier

Regex to validate Uniform Type Identifier

Uniform Type Identifiers (UTIs) are the modern method to identify file types on Mac OS X. In Apple's documentation it says:

A UTI is defined as a string (CFString) that follows a reverse Domain Name System (DNS) convention.

However, the UTI-related functions in LaunchServices do not provide any method to validate a UTI, i.e. check whether a given string is a UTI and conforms to the UTI string format (i.e. uses only legal characters, etc.).

The Wikipedia page on UTIs says:

UTIs use a reverse-DNS naming structure. Names may include the ASCII characters A-Z, a-z, 0-9, hyphen ("-"), and period ("."), and all Unicode characters above U+007F.[1] Colons and slashes are prohibited for compatibility with Macintosh and POSIX file path conventions.

What would a regex to validate a UTI look like?

Solution

Through some further searching I found this on the Reverse domain name notation Wikipedia page:

^[A-Za-z]{2,6}((?!-)\\.[A-Za-z0-9-]{1,63}(?<!-))+$

Concocted the following function to validate an NSString containing a UTI:

BOOL UTTypeIsValid(NSString *inUTI) {
    NSString *reverseDNSRegEx = @"^[A-Za-z]{2,6}((?!-)\\.[A-Za-z0-9-]{1,63}(?<!-))+$";
    NSPredicate *test = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", reverseDNSRegEx];
    return [test evaluateWithObject:inUTI];
}