Compared with iOS9, in iOS9. 1, Apple not only fixes bugs and increases system stability, but also adds some new functions, mainly including adding more than 150 (all models), fixing multi-task jam and real-time photo adaptation (6S/6S Plus). As for the other part, it is to fix the original bug of the system. In addition, the user's most concerned interface stuck problem has also been fixed, and the fluency has been significantly improved.

The update amount of iOS 9. 1 is about 300MB. If you are 6/6plus and haven't upgraded to IOS9, please don't upgrade, because even the best optimization is for 6S/6Splus, and the main configuration system of 6/6plus is IOS8. It is most suitable for each generation of mobile phones to use their own main distribution system. Nobody! If you have upgraded IOS9, you can upgrade IOS9. 1, because generally speaking, there is not much difference between the same series of systems, and upgrading is understandable.