It is advisable to connect your device directly via Wi-Fi to avoid data downloading charges over the 3G/4G connection of your smartphone.
After connecting the device via Wi-Fi, launch the Settings app select General tab and then tap on Software Update.
i OS 8 has been released to the public, and those who have been eager to update since Apple's WWDC announcement won't have to wait any longer.
Since i OS 8 promises to pack a bunch of new, really great features, it's time to present your options for getting on the latest and greatest for your Apple device.
You can download it if you like, but you don't need it to update i Tunes.
At this moment, go to Settings Software Update and then tap Install Now to begin installing the new update.They said, “it still not fix some old issues” like battery drain problem, Wi Fi connectivity issue didn’t solved in i OS 9.2.1.SEE ALSO : How to Downgrade i OS 9.2.1 to i OS 9.2 on i Phone, i Pad and i Pod Touch So if you hit any issue based on Apple new i OS 9.2.1 update, do let us via comment.Device Compatibility i OS 8.2 can now be installed as a free upgrade on numerous i OS devices, which are mentioned in the compatibility list below: NOTE: Jailbreakers are advised to hold back on the new update especially if they are running the older i OS 8.1.2 or lower versions which are still jailbreakable with Tai G, as Apple has reportedly patched up several exploits with the release of i OS 8.1.3 and fixed a few more in i OS 8.2 update.How to update your device to i OS 8.2 wirelessly Over the Air (OTA) Ensure your device is fully charged before you begin downloading the i OS 8.2 OTA update as it could take a few minutes up to an hour depending upon the server load and your internet connection speed.i Phone and i Pad users had reported lot of issues with i OS 9.2 update, including rear camera not focusing, can’t disable game center notifications, Email push not working, Wi Fi Issue, no message notification sound, unable send or receive text messages etc.