YouTube MP4 Grabber 2.0

gistfile1.m

-(NSString *)mp4URLFromYoutubeContents:(NSString *)string error:(NSError **)error {
        
    @try {
        
        NSString * (^getGETVariable)(NSString *url, NSString *val) = ^(NSString *url, NSString *val){
            
            NSArray *array = [url componentsSeparatedByString:[NSString stringWithFormat:@"%@=",val]];
            if ([array count] <= 1) return (NSString *)nil;
            
            val = [array[1] componentsSeparatedByString:@"&"][0];
            val = [val stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
            
            return val;
            
        };
        
        // first we shall find if the video is available and under 18
        if ([string rangeOfString:@"<p>This video may be inappropriate for some users.</p>"].location != NSNotFound) {
            
            *error = [NSError errorWithDomain:@"MusiParser" code:1 userInfo:@{ NSLocalizedDescriptionKey : @"This song requires you to be over the age of 18.  Musi can't stream it at this time." }];
            return nil;
            
        }
        
        // now that the video is there, we can parse the urls
        NSArray *array = [string componentsSeparatedByString:@"url_encoded_fmt_stream_map="];        
        NSString *urlStreamMap = [array[1] componentsSeparatedByString:@"\""][0];
        urlStreamMap = [urlStreamMap stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
                
        NSArray *streams = [urlStreamMap componentsSeparatedByString:@","];
        
        // for Musi, I like to get the lowest quality video for maximum streaming potential
        NSArray *qualities = @[@"small", @"medium", @"hd720", @"hd1080"];
        NSString *bestURL = nil;
        int lastIndex = INT_MAX;

        for (NSString __strong *stream in streams) {
            
            NSString *type = getGETVariable(stream, @"type");
            NSString *quality = getGETVariable(stream, @"quality");
            NSString *signature = getGETVariable(stream, @"sig");
            
            NSString *url = getGETVariable(stream, @"url");
            url = [url stringByAppendingString:[NSString stringWithFormat:@"&signature=%@",signature]];
            
            if ([type rangeOfString:@"video/mp4"].location != NSNotFound) {
                
                int index = [qualities indexOfObject:quality];
                if (index < lastIndex) {
                    
                    bestURL = url;
                    
                }
                lastIndex = index;
                
            }
                        
        }
        
        NSLog(@"[MusiParser] Returning Best URL to stream as: %@",bestURL);
        
        if (!bestURL) {
            
            *error = [NSError errorWithDomain:@"MusiParser" code:1 userInfo:@{ NSLocalizedDescriptionKey : @"No URL was found for streaming.  Are you sure this song can be played?" }];
            
        }
        
        return bestURL;
                
    }
    @catch (NSException *e) {
        
        *error = [NSError errorWithDomain:@"MusiParser" code:1 userInfo:@{ NSLocalizedDescriptionKey : @"No URL was found for streaming.  Are you sure this song can be played?" }];
        return nil;
        
    }
    
}