Get Youtube Video ID

+ (NSString*) getVideoID:(NSString*)linkString
{
    NSMutableString *predicateString = [[NSMutableString alloc] initWithFormat:@"%@", linkString];
    
    NSString *regexStr = @"[a-zA-Z0-9_-]{10}";
    
    NSError *error;
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexStr
                                                                           options:NSRegularExpressionCaseInsensitive
                                                                             error:&error];
    
    __block NSString *retunString = @"";
    [regex enumerateMatchesInString:predicateString options:0 range:NSMakeRange(0, [predicateString length]) usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){
        NSRange matchRange = [match range];
        matchRange.length = matchRange.length+1;
        //NSLog(@"matchRange.location: %d",matchRange.location); //31
        //NSLog(@"matchRange.length: %d",matchRange.length); //11
        //NSLog(@"result: %@", [predicateString substringWithRange:matchRange]); //tTfj05VNT40
        retunString = [predicateString substringWithRange:matchRange];
    }];
    
    return retunString;
}