Apple had already commented even at the WWDC opening presentation that one of the iOS 9 your convenience at the time of an update. See what the company highlighted on its website:
Smaller, more convenient updates.
IOS 9 does even more to efficiently stream new updates to your device without having to first download and unzip them, which means you don't need that much free space to update. And when the time comes for an update, you'll have new notification options that allow you to update your device while you sleep or while you're not using it.
Also according to Apple, iOS 9 requires 1.3GB of space on the device when it is released; comparatively, iOS 8 required 4.58GB.
Because to make this update process even easier, a new feature has emerged in iOS 9 beta 2 called App Deletion:
Well this is new. pic.twitter/BQKMDn5D6c
– Kaleb Butt (@Kaleb_Butt) June 23, 2015
As we can see in the image above, iOS 9 has a feature that automatically erases some applications from the device, freeing up enough space for the update to be downloaded and installed. After installation, deleted applications will be reinstalled (with all the necessary information).
Really cool, right? This new feature added to the Thinning app help a lot mainly users who have iPhones of 8GB and 16GB!