How to make an NSString path (file name) safe

This will remove all invalid characters anywhere in the filename based on Ismail’s invalid character set (I have not verified how complete his set is).

- (NSString *)_sanitizeFileNameString:(NSString *)fileName {
    NSCharacterSet* illegalFileNameCharacters = [NSCharacterSet characterSetWithCharactersInString:@"/\\?%*|\"<>"];
    return [[fileName componentsSeparatedByCharactersInSet:illegalFileNameCharacters] componentsJoinedByString:@""];
}

Credit goes to Peter N Lewis for the idea to use componentsSeparatedByCharactersInSet:
NSString – Convert to pure alphabet only (i.e. remove accents+punctuation)