Personally, I feel sending the code via SMS isn't all that secure. Unless you turn off "Show Previews" in Messages Options, the code will be displayed on your lock screen even with the phone locked. So if you loose your phone, 2 factor authentication becomes completely useless.
Get code via text or app? Any opinion?
Try an alternative code generator. OTP Auth can show the codes in the notification center in iOS 8 via a widget. In the latest release it can even insert the codes directly within Safari via an action extension.I'd always suggest getting a text. It can be slow to come through sometimes if your signal isn't great but some other systems require Google Authenticator which is an absolute pain to get the six digit code from within the app then enter in with enough time to spare.
When you go to use it, you have the choice. Sign up for both and you'll have more options when it's needed.
Update to this. With continuity in ios8, someone could steal your MB or ipad, have the code sent SMS, which shows up on their new screen
Personally, I feel sending the code via SMS isn't all that secure. Unless you turn off "Show Previews" in Messages Options, the code will be displayed on your lock screen even with the phone locked. So if you loose your phone, 2 factor authentication becomes completely useless.