When I add a link to a tweet in the TWTweetComposeViewController, I see the link attached correctly:

But unlike when I do so in Safari, the link doesn’t show a preview of the URL like Safari (or Youtube) does:

Do you know if it’s a hidden feature or if it depends on the Link added to the tweet?
Thank you!
This has been my experience as well, if you attach a URL the TWTweetComposeViewController will not automatically add a preview image.
I was curious so I took a look at the private runtime headers for Twitter.framework and I found a few interesting methods, including
- (BOOL)addURL:(id)arg1 withPreviewImage:(id)arg2;. Using this in my app I found it worked exactly as expected, the tweet view showed a link along with the image I included. Unfortunately this doesn’t help too much, since it’s a private method your app will almost certainly be rejected if you try to use it in the App Store.