Программное обнаружение ссылок на видео YouTube в Objective -C

Мне нужно загружать и сохранять видео с видеосайтов, таких как YouTube. Я хочу сохранить их в видеотеку iPhone. Как я могу обнаружить видео и сохранить их в библиотеке? Я уже проверил некоторые доступные исходные коды. Это то, что я сделал в действии загрузки, но не работает.

- (IBAction)download {
    [downloadButton setEnabled:NO];

    [webView setUserInteractionEnabled:NO];

    UIUserInterfaceIdiom userInterfaceIdiom = [UIDevice currentDevice].userInterfaceIdiom;

    NSString *getURL = @"";

    if (userInterfaceIdiom == UIUserInterfaceIdiomPhone) {
        getURL = [webView stringByEvaluatingJavaScriptFromString:@"function getURL() {var player = document.getElementById('player'); var video = player.getElementsByTagName('video')[0]; return video.getAttribute('src');} getURL();"];
    } else {
        getURL = [webView stringByEvaluatingJavaScriptFromString:@"function getURL() {var bh = document.getElementsByClassName('bh'); if (bh.length) {return bh[0].getAttribute('src');} else {var zq = document.getElementsByClassName('zq')[0]; return zq.getAttribute('src');}} getURL();"];
    }

    NSString *getTitle = [webView stringByEvaluatingJavaScriptFromString:@"function getTitle() {var jm = document.getElementsByClassName('jm'); if (jm.length) {return jm[0].innerHTML;} else {var lp = document.getElementsByClassName('lp')[0]; return lp.childNodes[0].innerHTML;}} getTitle();"];

    NSString *getTitleFromChannel = [webView stringByEvaluatingJavaScriptFromString:@"function getTitleFromChannel() {var video_title = document.getElementById('video_title'); return video_title.childNodes[0].innerHTML;} getTitleFromChannel();"];

    NSLog(@"%@, %@, %@", getURL, getTitle, getTitleFromChannel);

    [webView setUserInteractionEnabled:YES];

    NSArray *components = [getTitle componentsSeparatedByCharactersInSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet]];
    getTitle = [components componentsJoinedByString:@" "];

    if ([getURL length] > 0) {
        if ([getTitle length] > 0) {
            videoTitle = [getTitle retain];

            bar = [[UIDownloadBar alloc] initWithURL:[NSURL URLWithString:getURL]
                                    progressBarFrame:CGRectMake(85.0, 17.0, 150.0, 11.0)
                                             timeout:15
                                            delegate:self];

            [bar setProgressViewStyle:UIProgressViewStyleBar];

            [toolbar addSubview:bar];
        } else {
            NSArray *components = [getTitleFromChannel componentsSeparatedByCharactersInSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet]];
            getTitleFromChannel = [components componentsJoinedByString:@" "];

            if ([getTitleFromChannel length] > 0) {
                videoTitle = [getTitleFromChannel retain];

                bar = [[UIDownloadBar alloc] initWithURL:[NSURL URLWithString:getURL]
                                        progressBarFrame:CGRectMake(85.0, 17.0, 150.0, 11.0)
                                                 timeout:15
                                                delegate:self];

                [bar setProgressViewStyle:UIProgressViewStyleBar];

                [toolbar addSubview:bar];
            } else {
                //NSLog(@"%@", [webView stringByEvaluatingJavaScriptFromString:@"document.getElementsByTagName('html')[0].innerHTML;"]);

                UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"MyTube" message:@"Couldn't get video title." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

                [alertView show];
                [alertView release];

                [downloadButton setEnabled:YES];
            }
        }
    } else {
        //NSLog(@"%@", [webView stringByEvaluatingJavaScriptFromString:@"document.getElementsByTagName('html')[0].innerHTML;"]);

        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"MyTube" message:@"Couldn't get MP4 URL." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

        [alertView show];
        [alertView release];

        [downloadButton setEnabled:YES];
    }
}