I've started using 2-factor authentication with a bunch of services. So, after I sign in, I get an authorisation code SMS'd to me. Now, if my phone is locked, I really don't want code appearing on the lock screen, but I generally like showing the SMS preview.
I noticed in Notification Center -> Messages, there is a choice:
Show Alerts from Everyone
Show Alerts from My Contacts
Now, I assumed that if I chose, "Show Alerts from My Contacts", but kept "Preview" on, if the SMS sender wasn't in my address book, I wouldn't see the Alert, and certainly not the Preview on my lock screen. However, I can't find any discernible difference between these two settings.
Every SMS I get from numbers NOT in my address book, I see the banner if the phone is unlocked, and I see the Preview if it is locked, and I see the Preview on the Lock Screen in the Notifications pulldown.
What gives? Am I misunderstanding the functionality of this setting?
It's an iPhone 5S, running 7.1 (11D167)