There are 2 ways to upgrade iOS 6 to iOS 7, namely over the air and through iTunes. Here, we just talk about the first way.
Note: iOS 7 can only be available for the iPhone 4 and the newer.
Before upgrading, we should do some preparations:
1. Upgrade out-of-date apps since these apps may not work in iOS 7.
2. Check whether your iPhone has enough free storage space, because the upgrading requires at least 1.4 GB free space to store the download temporarily. Through tapping Settings, General, and Usage successively, you can know how much free space is left.
3. Copy important data like photos, music, contacts, and videos to computer in case of accidents.
4. Connect wall charger since the upgrade will cost much time.
After making these preparations, we can upgrade iOS 6 to iOS 7 over the air. Since the update has been released, we can find corresponding notification on the screen of iPhone. Please tap Settings – General – Software Update to check whether the update is available. Then, your iPhone will check if the iOS 7 is available. If it is available, you can tap Download to download the iOS 7 update. After that, tap Install to upgrade iOS 6 to iOS 7. After installation, upgrade is finished successfully.