If you're worried about someone accessing your Facebook account from a different iPhone, iPad, or computer browser, you can enable a few security settings to set your mind at ease. Code Generator can give you access codes right on your iPhone and iPad so you can approve different devices and browsers as you see fit.
Before continuing, you'll need to make sure that Login Approvals are turned On for your Facebook account. You'll most likely need to do this via a desktop computer or the full version of the site via Safari on your iPhone or iPad. You can find Login Approvals under the Security Settings section of Facebook.
After you've done that, continue on.
On an already authorized iPhone or iPad, launch the Facebook app.
Tap on the Menu button in the upper left hand corner.
Scroll all the way down and tap on Code Generator.
Tap on Activate if you are asked.
You'll now be given a six digit code that you can enter into the new device in order to grant it access. It will re-generate every 30 seconds so make sure you're watching for what code you need to enter.
Now attempt to log in to the Mac, iPhone, iPad, or PC that you'd like to authorize to your Facebook account.
You'll notice that you are asked for a code. One will be texted to your phone or you can use any code generated by Code Generator. Enter it once you have it by follow the steps we just covered above.
That's all there is to it. Code Generator is great for times you may not have cell service but can access WiFi from one of your already authorized devices. Facebook will always send you a text authorization code to whatever cell phone number you have on file but if for some reason you can't access it, Code Generator will do the trick too.