Today Apple released iOS 9. The newest iteration of Apple’s mobile device operating system is available now for all iOS devices from the last few years (full list of compatible devices here). One of the key features of iOS 9 is improved storage management. That is to say that the OS itself is designed to take up less of your precious storage space. To install it though, you will need a good amount of free space. More than many users of 16 or 8gb phones have readily available.
To upgrade to iOS 9 on a device that’s out of storage, we can make a backup, then erase the phone, perform the upgrade, then restore all the data back from the backup. This entire process will take several hours, so make sure you can allow a few hours where you’ll have great wifi and won’t need to make calls.
First, let’s make a safe backup of the phone.
You can back up in two places, iCloud or iTunes. In my experience, iCloud is much more reliable for device backups, so I will walk through that process
Your device should be backing up every night while its charging, but we need to make one last backup before performing a big upgrade. Launch the Settings app, tap on iCloud, then scroll down until you find the Backup option and tap on it. As long as you’re connected to a wi-fi network, a “Backup Now” button will become active after a brief moment. Tap that button.
Now that we have a safe backup of the device, we can make it ready for the iOS 9 download. To do this, we are going to completely erase the phone. So go to Settings, then General, then scroll to the very bottom and tap Reset. Then select “Erase all content and Settings.”
You will need to confirm, and if you have Find My iPhone enabled, you will have to disable it. Then the phone will restart and come back up as a fresh copy of the software.
You will have to connect the phone to wifi, choose the option to Set up as a new phone, then skip signing into iCloud, skip setting up Touch ID, and just kind of skip through to the main screen. Once at the main screen, go to Settings, then General, then Software Update.
Go ahead and Download and Install the software update. Once that finishes (it will take a while, depending on your internet speed), you will once again erase the iPhone. To do this, we are going to completely erase the phone. So go to Settings, then General, then scroll to the very bottom and tap Reset. Then select “Erase all content and Settings.” You will need to confirm, and if you have Find My iPhone enabled, you will have to disable it. Then the phone will restart and come back up as a fresh copy of the software.
Now you will have a fresh install of iOS 9, with none of your data in place. To restore all of your data, sign into iCloud, then set up the new phone as a restore of the backup we just made.
Over the course of the next couple hours, all your stuff will download back to your phone like magic, and you will have iOS 9 without having to delete all your pictures and music from your phone.