Since a functional "update" is impossible, here is how to keep messaging alive on your classic iPhone.
Keep your iPhone 4s on iOS 7.1.2 as a time capsule—a beautiful example of skeuomorphic design and smooth scrolling. Use it for music (iTunes Match still works), old games (Infinity Blade), and iMessage (Apple still supports legacy iMessage accounts). But for WhatsApp?
He connected the phone back to the computer. He dragged the old .ipa file into iTunes and hit "Sync."
