This project is not being maintained.

HCYoutubeParser

HCYoutubeParser is a class which lets you get the iOS compatible video url from YouTube so you don't need to use a UIWebView or open the YouTube Application.

It's really simple to get going

// Gets an dictionary with each available youtube url
NSDictionary *videos = [HCYoutubeParser h264videosWithYoutubeURL:[NSURL URLWithString:@"http://www.youtube.com/watch?v=8To-6VIJZRE"]];

// Presents a MoviePlayerController with the youtube quality medium
MPMoviePlayerViewController *mp = [[[MPMoviePlayerViewController alloc] initWithContentURL:[NSURL URLWithString:[videos objectForKey:@"medium"]]] autorelease];
[self presentModalViewController:mp animated:YES];

// To get a thumbnail for an image there is now a async method for that
[HCYoutubeParser thumbnailForYoutubeURL:url
                          thumbnailSize:YouTubeThumbnailDefaultHighQuality
                          completeBlock:^(UIImage *image, NSError *error) {
    if (!error) {
        self.thumbailImageView.image = image;
    }
    else {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:[error localizedDescription] delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil];
        [alert show];
    }
}];

Warning: This is not approved by the ToC of YouTube. Use at own risk.