Q: Now that I can re-download previously purchased apps at will with iCloud, I am wondering if there is any purpose in syncing my iPhone’s apps with my iTunes library? Before iCloud, I would make sure to keep every purchased app in iTunes in order to be able to reinstall them in the future. Is there any other utility to having all my apps in iTunes? If there is no other purpose to syncing apps, is it safe to simply uncheck the “Sync Apps” checkbox in iTunes and delete all the IPA files from my iMac?
A: The first and most obvious reason to keep your apps around in iTunes is simply to have a local, extra backup of them in the event that something happens to your iOS device. Although you can re-download your apps using iTunes in the Cloud and restore them as part of an iCloud Backup, this is not without its limitations.
Firstly, iCloud will only restore your apps if they are still being sold on the iTunes Store. If an app has been removed from sale—either by Apple or by the developer—then you can no longer re-download that app. This includes not only re-downloading the apps again but also recovering them after restoring from an iCloud Backup. Apps that you have on your device, or in your iTunes library, will continue to work regardless of whether they’re still available on the iTunes Store, but your local copies will suddenly be the only way you can ever reinstall those apps.
Installing or restoring large apps via a USB connection from iTunes (e.g. navigation apps, large games like Infinity Blade II, etc) will naturally go much faster than trying to do the same over the air. This can also be especially significant if you have more than one iOS device for yourself or other family members, as a single copy in iTunes can be installed on multiple iOS devices, rather than requiring each device to download (or re-download) the app separately.
Keep in mind also that your apps themselves are not actually stored in your iOS device backups. When restoring an iOS device, the apps are simply reinstalled from the same source method as the backup—synced from iTunes if you’re restoring an iTunes backup or synced from iCloud if you’re restoring an iCloud backup. This means that if you’re backing up your iOS device to iTunes, then you also need to keep your apps in iTunes in order for them to be automatically put back onto your device during a restore.
Another important but somewhat less obvious reason to keep a local copy of your apps is to protect yourself from problematic app updates. If a new version of an app is causing problems for your device, you can more easily fall back to the old version on your computer—as long as you haven’t updated the version in iTunes or you’re backing up your “Mobile Applications” folder. It is not uncommon for new updates to remove favourite features from older versions or developers to drop support for older iOS versions—in fact there have been a number of apps where developers have told users in the release notes to backup and keep their old copy of the app if they’re still using an older iOS device.