Visually Rich Links Tutorial for iOS: Image Thumbnails

Mar 30 2020 , Swift 5, iOS 13, Xcode 11 Swift 5, iOS 13, Xcode 11

Generate visually rich links from the URL of a webpage. In this tutorial, you’ll transform Open Graph metadata into image thumbnail previews for an iOS app. By Lea Marolt Sonnenschein.

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Visually Rich Links Tutorial for iOS: Image Thumbnails

35 mins

Visually rich links describe beautiful imagery, typography and even video thumbnails used to preview web page content. They’re a significant upgrade from blue text, which was the only thing available before iOS 13.

Regular vs rich links.

In this tutorial, you’ll use the LinkPresentation framework to make links better looking, more engaging and more user friendly. Check out this example of a video thumbnail preview:

Rich link preview with video.

All a web page has to do is add a couple of special HTML tags to specify the title, icon, image or video and voilà: Your links come alive!

Just imagine how nice it’ll be for your messaging, blog or recipe app to immediately show a preview of the content the user’s about to see. You’d click on the right link much faster than the left, even though they link to the same web page.

Regular vs rich link.

With the addition of the LinkPresentation framework, you can easily and quickly showcase links in your apps. Ready to dive in?

In this tutorial, you’ll learn how to:

  • Create rich links.
  • Handle LinkPresentation errors.
  • Store metadata.
  • Optimize the share sheet.
  • Save favorite links.

Getting Started

In this tutorial, you’ll be working on an app called Raylette. Each time you spin the wheel, Raylette randomly chooses a raywenderlich.com tutorial and presents it to you using the LinkPresentation framework.

Final app screenshots.

Hopefully, it inspires you to check out a topic you might not have come across otherwise!

Use the Download Materials button at the top or bottom of this tutorial to download the starter project. Open it and build and run. You’ll see you already have a Spin the Wheel button and two tabs: Spin and Saved:

Begin app screenshots

Before you dive into the code, though, there’s a bit of theory to cover. So hold on tight!

Understanding Rich Links

Rich links are link previews you see, for example, when users send messages through the Messages app.

Depending on the information Apple can extract from the web page, a link preview can look one of these four ways:

Various rich link views based on web page tags.

Understanding Rich Links: Web Page Metadata

The web page’s metadata dictates what you’ll see in the preview. Look at the tags in the <head> section. You can do this in Chrome by right-clicking on a web page and choosing View Page Source.

Context menu in browser View Page Source

Here’s an example for the Flutter Hero Animations tutorial from raywenderlich.com:

<head>
<title>Flutter Hero Animations | raywenderlich.com</title>
<meta property="og:title" content="Flutter Hero Animations">
<meta property="og:type" content="video.other">
<meta property="og:image" content="https://files.betamax.raywenderlich.com/attachments/collections/222/0c45fb39-9f82-406f-9237-fc1a07a7af15.png">
<meta property="og:description" content="<p>Learn and understand how to use the Hero widget in Flutter to animate beautiful screen transitions for your apps.</p>
">
<meta property="og:site_name" content="raywenderlich.com">
<link rel="icon" type="image/png" href="/favicon.png">
...
</head>

The metadata that powers rich links consists of both Open Graph meta tags and other HTML tags. The LinkPresentation framework extracts all these tags and uses the most appropriate ones.

Understanding Rich Links: Open Graph Protocol

The Open Graph protocol is a standard of web page meta tags for visually rich links in apps like Facebook, Twitter or Messages:

Examples of how rich links are presented on Facebook, Twitter and Messages

Conforming to the protocol is pretty simple. You just need to add some special <meta> tags in the <head> of your web page and you’ll be up and running in no time.

The <meta> tags required by the Open Graph protocol are:

  • og:title: object title
  • og:type: object type, for example music, video, article and many more
  • og:image: the object’s image URL
  • og:url: the canonical URL of the object

You can easily recognize the Open Graph <meta> tags by their og: prefix.

The majority of raywenderlich.com articles and video courses have code like this. Each web page has the following tags: og:title, og:type, og:image, og:description and og:site_name.

Check out the full specifications of the Open Graph protocol to learn more about how it works and what types it supports.

Note: og:site_name specifies that a particular web page is part of a larger website. In our example, it tells us Flutter Hero Animations is part of the larger raywenderlich.com website.

Building the Preview

The LinkPresentation framework extracts the metadata from all the web page’s tags and uses the most appropriate ones to display the best preview.

Which tags generate which link previews.

The preview depends on five pieces of information:

Building the Preview: The URL

The URL comes from either:

  • The site’s URL
  • og:site_name like <meta property="og:site_name" content="raywenderlich.com">

When og:site_name is present, it takes precedence over the URL in the link preview. All Open Graph meta tags take precedence over the other alternatives when they’re present.

Building the Preview: The Title

The title comes from either:

  • <title>Flutter Hero Animations | raywenderlich.com</title>
  • <meta property="og:title" content="Flutter Hero Animations">

<title> specifies the title of the web page you see in the browser. But sometimes, the <title> tag duplicates the site’s URL, as in this example. To avoid this duplication in your preview, use og:title instead. It will take precedence over the <title> tag.

  1. Keep titles unique and informative.
  2. Avoid duplicating the site name in the title.
  3. Don’t generate tags dynamically, because the LinkPresentation framework doesn’t run JavaScript.
Apple recommends you:

Building the Preview: The Icon

The icon comes from this tag: <link rel="icon" type="image/png" href="/favicon.png">

Building the Preview: The Image

The image comes from this tag: <meta property="og:image" content="image.png">

  1. Use images specific to your content.
  2. Avoid adding text. Rich links appear in many sizes across multiple devices; the image text might not scale.
  3. Specify an icon even when you have an image, as a fallback.
Apple recommends you:

Building the Preview: The Video

The video comes from this tag: <meta property="og:video:url" content="video.mp4">

  1. Keep the size of the icon + image + video to 10MB or less.
  2. Reference video files directly, rather than YouTube links, which will not autoplay.
  3. Avoid videos that require HTML or plug-ins; they are not supported.
Apple recommends you:

All of these, except the URL itself, are optional. The LinkPresentation framework will always choose the “richest” information possible to present the link preview in the best way. The order of “richness” goes from Video > Image > Icon.

And with that, you’re finally ready to jump into the code!