As many folks know that it’s better to do clean install of iOS if there is a new release version such as recently iOS 9 released. Because I’m too busy with some works at office and studying some course materials, I just click install the software update through OTA . I like the iOS 9 because it’s faster and good battery life. But there is a bug that runs every apps installed on the iPhone after the iPhone was restarted, so it makes iPhone run slowly and consuming much battery :(.
For that reasons, I decide to do clean install and it works well like charm :). I’m happy with the new iOS 9.
If you’d like to know how to do clean install of iOS 9, the basic concept is same with this