How to set up iCloud two-factor authentication
Set up two-factor authentication for iCloud
This feature isn't specific to iOS 8, but it is important for securing your iPhone. Just before iOS 8 rolled out, Apple expanded the number of iCloud features protected by two-factor verification. You can now add a second layer of protection to your iCloud account that will protect it against snoops.
What does this second layer look like? When you sign into your iCloud account, and after you enter your regular password, Apple will send a text message to the mobile phone you've registered as your two-step verification device. The text message will have a randomly generated numerical code that will expire in just a few minutes. You'll need to enter this code to get into your account.
Even if someone were to know or guess your iCloud password, he or she would also need your smartphone to get into your account. Two-step verification adds an extra minute or so to your login time, but greatly increases your security.
1. On a computer, go to www.appleid.apple.com.
2. Click Manage Your Apple ID.
3. Enter your Apple username and password.
4. Click Password and Security.
5. Answer your security questions if you're prompted to do so.
6. Under Two-Step Verification, click Get Started.
7. Click Continue.
8. Click Continue.
9. Click Get Started.
10. Click Add a Phone Number.
11. Enter your phone number in the popup box. Then click Next. Apple will text that phone number with a four-digit verification code.
12. Check for the verification code Apple texted you. Remember that this code expires after a short time, so enter it right away.
13. Enter that verification code into the boxes provided. Then click "Verify."
14. You will now see that phone number listed as a Verified Device. You can repeat the process with other trusted devices as well, so you can get two-step verification codes sent to other devices.