IOS 9.2.1 is a point update to iOS 9.2, which was also a minor update with several under-the-hood changes.The official release notes for iOS 9.2.1 states the update to contain security updates and bug fixes.
In this post, we will teach you how to update iPhone 4 to iOS 9 with all the basic prerequisites. While iPhone 4s is no longer compatible with the new iOS 11, you can still get iPhone 4s iOS 9 without much trouble.
