How to get thumbnails from any URL in iOS?

Question

In both chat apps, social apps have a feature, when we paste a link on text view it's giving us a thumbnail from that url,

Is this possible to do in an iOS app. If it is how may I do this?

Answer 1

I would parse html content and try to find links to .png, jpg etc files. Then check the resolution to exclude very small images or those specified as a background in css. As a result a user would get a list of filtered images like on the screenshot you attached.

As a parser you could use https://github.com/nolanw/HTMLReader

Answer 2

Pages like Facebook use OpenGraph information from web pages to generate thumbnails for links. OpenGraph attributes describe the object presented on a web page. OpenGraph data is stored in meta tags, as shown in A.Krasniqi's answer:

<meta property="og:title" content="The Rock" />
<meta property="og:type" content="video.movie" />
<meta property="og:url" content="http://www.imdb.com/title/tt0117500/" />
<meta property="og:image" content="http://ia.media-imdb.com/images/rock.jpg" />

These meta tags have a prefix of og.

Basic OpenGraph attributes include:

• og:title (The title of the object)
• og:type (The type of the object, e.g. video.movie)
• og:url (A permanent, canonical URL to this object)
• og:image (An image representing the page)

Other tags include:

• og:description (A description of the object)
• og:video
• og:audio

All OpenGraph parameters are documented here

To parse these, you can use NSXMLParser but others have implemented OpenGraph parsers. (Just google "iOS OpenGraph parser")