Yeah, you read it correctly, with the latest update of WhatsApp for iOS, it is possible to reply to messages without going online and changing your last seen timestamp.
With the WhatsApp update( version 2.12.10) for iOS which came on November 2nd, the feature to quickly reply to messages right from notification is incorporated. Earlier in iOS 8, this feature came for Messages app and now you can reply from notifications for WhatsApp messages too which will definitely save a lot of time. Moreover, this feature has an extra added benefit or use so to say.
Note: With WhatsApp update in August 2016, on using this method you will be marked online and last seen time stamp will be changed/updated. However, you can still use this method to reply to a message quickly without opening WhatsApp.
Latest Update: WhatsApp now allows sending messages offline which we can be used to send WhatsApp messages without changing last seen.
Send message in WhatsApp without going Online
Reply from notification feature allows you to send/reply to messages without going online in WhatsApp. Hence replying from notification will not even change your Last Seen time stamp. Here are the multiple ways you can reply from notifications for WhatsApp messages.
Send message without opening WhatsApp
Just drag down the notification to type your reply as shown in the image below and Tap on Send. It is similar to notifications for Messages app.
To send Message in WhatsApp without changing Online status for Android you can read the following article: Send message without opening WhatsApp.
Send message in WhatsApp without changing Last Seen
If you get a WhatsApp message notification on the Lock screen when iPhone/iPad is locked then you can simply swipe towards left of the screen on the notification and Tap Reply as shown below.
Reply from Notifications for WhatsApp
If you somehow miss the notification which comes on top of the screen. You can swipe down and go to Notifications Tab. Under the notifications tab swipe left on the message and select Reply.
The feature to send WhatsApp messages quickly from notifications is quite useful for me. However, I don’t bother much about Last Seen and Online Status, just an observation so wrote about it. Is sending a message in WhatsApp without going Online useful for you?