Since iOS 7, Dynamic Type has allowed users to choose a prefered font size for their phone. At Airbnb, we try to build an app that our entire community can use — since Dynamic Type is a critical accessibility feature, we knew supporting it would make more people able to effectively use our app, some of them probably for the first time. To validate the importance of this feature, we examined the data and saw as much as 30% of people using our app had a preferred font size that was not the default. This usage is not skewed towards particular sizes, but evenly spread across larger and smaller than default. It turns out, supporting this preference creates a consistent experience across the OS that users will notice. Experimenting with Dynamic Type on individual features in the Airbnb app resulted in a significant increase in engagement, helping move our bottom line metrics. If you spend the time to support Dynamic Type in your app too, users will surely thank you for it! Going beyond the metrics, supporting Dynamic Type holds your UI components to a higher level of quality. Layout will need to be robust enough to handle a wide range of preferences, similar to variations created by localization and device screen size. Since much of our development time is spent on single devices and languages, bugs only reproducible in certain configurations will too often slip through. Fortunately, many of these are now being caught during Dynamic Type testing. If you already support varying screen sizes through UITraitCollection and translations with various length strings, there’s a good chance you’ve done most of the work to support Dynamic Type.