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I was wondering how social networking apps, such as Twitter, Facebook and WhatsApp update their user interface in real-time when another user interacts with the user of the app. To use the best example I can think of: when you have a chat window open in WhatsApp, the UI updates automatically (without any user actions required) when the user you're chatting with interacts with you. Messages appear on your screen without refreshing and the "last seen" status at the top of the screen updates automatically when your chat partner either goes offline or comes back online. I can think of two ways to achieve this:

  1. Remote push notifications: this approach strikes me as the 'cleanest' way to do this, but it's probably also the riskiest way. Using silent notifications (content-available) to pass data to another device at the moment a user does something, would probably save you a lot of HTTP requests and therefore would make your app consume a lot less data and CPU usage. The risk of this approach is that a user can easily disable ALL push notifications to save battery power (including silent notifications) and then your app wouldn't be able to get notified on events remotely.
  2. Local UI refreshing: This approach is obviously the safest, but I think it's really 'nasty' and eventually everyone would feel the downside of it. Constantly refreshing the UI and re-retrieving data from the database to make sure the latest messages and statuses are displayed to the user would be safe in the way that your app doesn't have to rely on the device's battery and background mode settings, but the downside is that this will make your app consume a lot of data and battery power, which would be bad for the user's data plan and his device. I also don't think Apple would approve of an app that's consuming so much data and power.

I've just implemented a chat function into my own app, and I want to enable the same real-time UI updating that WhatsApp uses. What would be the best way to do this? Should I use one of the two methods above or can someone think of another way to do this? By the way, I'm a relatively new programmer who just recently learned how to develop iOS apps (Swift). I'm very far from being a pro, so please go easy on the explanations and work method capabilities. Thanks!

rmaddy
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Mark Carols
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1 Answers1

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The chat apps make use of WebSockets to create a constant connection with the client and a backend server.

This article on Appcoda can help you start learning about Socket.io. It answers your questions and also helps you to create a demo app.

Puneet Sharma
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    Thanks! I didn't know such thing existed. I thought chat apps had to take care of their client-server communication manually. I'll check out the article. – Mark Carols Jul 11 '17 at 05:33