After a month of iOS 8.1.1 release on 17th Nov, Apple has released iOS 8.1.2 for some minor bugs fix, as referring to the file size of 25MB, it also means iOS 8.1.2 is not a major update.
To update your Apple iOS 8.1.1 to iOS 8.1.2, follow the steps below;
Before update, make sure you have full power or at least 70% of power, otherwise you can have the iphone charging and perform the update.
1. Tap of Setting
2. Tap on General
3. Tap on Software Update
4. Checking for Software
5. Download the file and install
6. Wait for the iPhone, iPod, iPad to reboot and taking the new updated software into your device.