A new iOS 9 feature added in beta 1 was only discovered when users attempted to update to beta 2 earlier today. This new feature will allow the operating system to intelligently delete applications if you don’t have enough free space to perform a software update. Once the update is complete, the apps will automatically be reinstalled and your data will remain intact.
The feature is designed to accompany another iOS 9 tweak that was announced during the WWDC keynote that enables Apple to push out much smaller updates that require less free space.
Other space-saving features introduced in the new OS include “app thinning,” which allows developers to distribute only the necessary portions of their apps to users, and Swift libraries built-in so developers don’t have to include them with every app.