Apple has released an update for the iOS for the various Apple devices, and it is the Apple 6.1.2 version update made available to remove the Exchange calendar bug that was known to have the connection active for long, and thus eating up a lot of battery. This was an issue that was not to fix by itself or the app update, thus the entire iOS system was sent an update, and it is the 6.1.2 version of iOS that is available now, and the size is a few MB so the update would take no more than a few minutes.
To update your iOS device to the 6.1.2 version, go to Settings and you would see the section “General”, under which you need to go to “Software Update” and check for any available update.
Once you check for the update, there would be an update available with the info about the update, where you need to hit “Download and Install” for the update to happen. It is always recommended that you take a backup for any size or any type of iOS update, because one cannot guarantee that the data would be safe and restored back by itself if the update doesn’t happen successfully. Accept the Terms and Conditions, and the update process would start before a battery pop-up confirms it.
Once you agree to the terms and conditions, the iOS device would show a pop-up suggesting you to connect the device to the power, or would ask whether you want to continue the upgrading without connecting to the power. Once you hit continue, the update process would start and it would initially download, later prepare for the update and then the device would restart while the update is happening.
It was not much long ago that the Apple iOS 6.1 was out, but the battery draining issues made the Apple team work onto a small update which makes the battery drain lesser due to the Calendar Exchange. Check how to Jailbreak iOS 6.1 on any of your Apple device using the Evasion tool.