The stock Messages app offers many 3D Touch shortcuts on the new iPhones. One of the 3D Touch shortcut allows users to read recent conversation without even opening a thread. Users can also peek on a Messages thread and read the latest message. What makes this feature even more useful is that on iOS 9 when you peek to read a message, the ‘Read’ report is not sent to the sender of the message, even though you have already read it. This means you can read a message without letting the person on the other know you have read his or her message. This is super useful in scenarios when you want to reply at a later time but you don’t want the person on the other end to feel ignored.
Here’s how to do it. Open the messages app and scroll to the iMessage thread whose message you want to read without sending the read receipt to the sender. Force tap and hold on it to get the peek or preview of the messages. Be careful not to pop the iMessage thread, as if you do so the Read receipt will be sent right away. You can also swipe up while holding to bring up the options menu, which will allow you to read messages more comfortably.
While iOS users have been able to get the preview of a message without sending a read receipt before through lockscreen notifications, banners and notification Center, this is the first time they will be able to read the whole message. Needless to say it is limited to iPhone 6s and iPhone 6s Plus as it requires 3D Touch feature.