String to BOOL extended function

string2bool.m

- (BOOL) string2bool: (NSString*) aString {
    NSString *normalizedString = [self normalize: aString];
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern: @"(yes|true|tak|ok|right)"
                                                                           options: NSRegularExpressionCaseInsensitive
                                                                             error: NULL];
    return [regex firstMatchInString: normalizedString options: 0 range: NSMakeRange(0, normalizedString.length)];
}

// [aString boolValue];