A few days ago I accidentally cracked the back of my iPhone 4. For a piece of tech that I rely on and use multiple times a day, it's no fun to use while sharp shards of glass are sticking out of it. Here are a few tips on what you can do if the back of your iPhone 4 breaks.
The first thing to do as soon as your iPhone back breaks is to tape it down. A clear piece of packaging tape will work just fine. If you don't have tape on you but happen to have a screen protector on your iPhone, you can take that off and stick it onto the back. You can always buy a new back plate, but taping up the back is a quick and easy fix when you're out and about—the last thing you want is to have shards of glass in your pocket. From here you have three options:
1. Take it to an Apple store. Apple doesn't advertise this, but if it's your first time breaking the glass back, they will replace it for free while you wait. Your results may vary depending on the Apple store, but make sure you make an appointment online first so you won't have to wait too long.
2. Replace it yourself. Luckily for me, the glass back that broke was actually a replacement back that I had swapped out with the original. I've seen more than a few people crack their iPhones, so I took some preventive measures by swapping the original back a long time ago (and it was a good thing I did). You can find an original replacement back or take the opportunity to look for something different like a metal back or a transparent one. You can check out ifixit.com's tutorial for how to install the rear panel.
3. Keep it as is. If you don't live by an Apple store or don't want to go through the trouble of replacing the back plate yourself, you can always manage just fine by covering it up. Simply buy a screen protector film for the back or put it in a slider case.