This is an update for the 2-step verification for Google account which i posted before. The Google Authenticator app is so much overrated but nevertheless helpful that i'd cry if i'll lose my iPhone.
The process is so simple: launch the app, then enter the code into the Google prompt whenever you're accessing your big G accounts to other computers or devices.
As of this writing, Neither the app has been updated nor a new version is available. Go grab your free copy from the APP STORE and let this manage your account verification for Google. What makes this app essential is the ability to generate codes without having to access the internet. Once you've launched it, you must enter the code a.s.a.p. before the timer ends (see pic above).
PS: i always recommend to always have a printed copy of your Google verification codes where you can access it easily. Don't forget to always have a substitute of these codes in cases where your iPhone is not available by saving an image file of these codes and drop 'em on your cloud storage like DropBox.