Congratulations, you have successfully created an application that runs on all iOS devices and screen sizes. You took an application that had just a single page and turned it into a simple contacts application with a detail view. To achieve this, you made use of Auto Layout and traitCollections. You learned about size classes and what they tell you about the available screen's real estate for your application. You also learned how to make use of Auto Layout through code and how to respond to changes in your app's environment in real time. Finally, you learned how to simplify a lot of the Auto Layout work you've done by implementing UIStackView. To top it all off, you saw how prepare(for:sender) allows you to pass data from one view controller to another.

The lessons you've learned in this chapter are extremely valuable. The increase in possible screen...