Either way you choose to back up, once you’ve installed iOS 9, you’ll have all of your photos, apps, and other data stored safe and sound.
Leave a way back
Don’t get stuck using an OS you can’t stand—be sure to have a copy of the latest version of iOS 8 compatible with your device. There are invariably cases where people wish they hadn’t upgraded—perhaps because an app they rely on hasn’t yet been updated for iOS 9 or, as it turns out, they hate change (or their older device runs more slowly with the new OS). If you act quickly, you can put things back the way they were.
Here’s the deal: Apple “signs” versions of iOS. This tells the device that the version you wish to use is OK to use with that device. While that version is signed, you can install it on your iOS device—even if it’s a version of the operating system that’s earlier than the one you just installed.
However—and this is very important—Apple traditionally stops signing old versions of iOS just a day or two after releasing major updates (such as iOS 9). If you were to update to iOS 9 say, a week after it ships, you might find that you can’t go back to iOS 8.
If you have a copy on your hard drive you will find it, by default, by following this path: youruserfolder/Library/iTunes and then select the Software Updates folder for the relevant device. (You access the Library folder in your user folder by holding down the Option key in the Finder and choosing Go > Library.)
The Mac will delete this files under certain circumstances so you may not have a copy of the latest one. If not, launch your favorite web browser and search for “download ipsw.” You’ll find a number of sites that offer links to the file you need. Just be sure to choose the correct one based on the device you’re using.
Remember, this window stays open for a very limited amount of time, so you’ll have to act quickly if you want to get back to iOS 8.
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