Why iOS 5 Apps Sometimes Say They Are "Cleaning" Themselves

With iOS 5, iPhone and iPad users started noticing a new curious behavior: app icons that suddenly started "Cleaning…" themselves. Facebook does it. Instapaper does it. Even Twitter does it. But what the heck does it mean?

I'd long wondered about that myself, but as it turns out, it has to do with iOS 5 deleting cache and temporary files to make the backup as small as possible… perfect for shooting up to the iCloud or to your Mac through iTunes WiFI sync.

TiPB has the details, which I really enjoyed:

Since adding iCloud and Wi-Fi sync options, it's become important to keep app data as clean as possible, so backups are as efficient as possible, so we're not left waiting around for minutes or hours getting as frustrated as possible.

And yes, this is the same reason that, under the original iOS 5.0, apps like Instapaper would sometimes lose all your locally cached articles. (Since fixed with the addition of a third storage option between documents and cache, one that's not cleaned but also not backed up.)

There you have it! It's nothing to worry about, it's all part of iOS 5 purging itself of toxins from time to time.