How Coursera Uses VIPER to Architect Transitions Between App Features

Oy vey, now there’s a ton of AltConf 2015 talks online, too! So much to digest! In “250 Days Shipping With Swift and VIPER by Brice Pollock, he shows how the folks at Coursera do some clever things with the VIPER iOS app architecture: they use a Router which handles internal URLs.

These URLs are strings captured in an enum. Each routable component responds to routing requests with a success or failure indicator.

The routable components are called “View Compontents”. A View Component, according to Brice, is made up of a View (a protocol implemented by the UIViewController), a View Model, a Presenter (and Event Handler), and an Interactor. Some of these terms are taken from VIPER.

A feature of an app, like logging in or displaying stats, is probably a combination of multiple View Components, but that’s just a guess. Don’t confuse this concept of uppercase View Components with actual view components (lowercase, see?), which are UILabels and the like.

At about 10:50, Brice shows how events within a View Component are handled. In case you haven’t tried VIPER, yet, that part should be pretty instructive.

So instead of transitioning from one UIViewController to the next, you would model a transition from View Component A to B, including switching Views or view controllers.

As I said a while ago: an architecture like this doesn’t work well with Apple’s built-in mechanisms, like Storyboard Segues. I guess there’s room for a VIPER-inspired app template to reduce architecture overhead per app. A framework won’t be a good fit because there are so many places where you will want to customize how things are done.

Watch his presentation, it’s worth it!

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