July 27, 2012, 3:49 PM — Here's how to stop prying eyes from seeing text messages or imessages that could appear on your iPad or iPhone's lock screen.
1. Open the Settings app.
2. Go to Notifications.
3. Tap on Messages.
4. Scroll down and toggle the Show preview option to the Off setting. This will let you see that a message has arrived and who sent it, but it won't display any part of the message itself.
5. To stop texts and imessage notifications from appearing altogether on your lock screen, toggle the View in Lock Screen setting to the Off position.
For more, see the original article at the link below.
Keep Your iMessages Private On Your iPhone or iPad | Cult of Mac