Triggers in Parse Server using Swift

Question

Recently, I was tasked to do a simple chat app for iOS, using Swift.. So, I have a parse server ready and running! All I want to know, is how to use triggers..

Let's say I have opened a conversation and I just received a new message. How can I get it, without constantly checking for new messages? I saw that cloud code is probably the way to go, but if it is so, is it practical? I mean, if I have 5000 users and they are constantly chatting, will it perform well?

Thanks in advance!

Answer 1

You want to use Parse LiveQuery component.

1. Add Live Query to your server's config:

   let api = new ParseServer({
     ...,
     liveQuery: {
       classNames: ['Test', 'TestAgain']
     }
   });
   
   // Initialize a LiveQuery server instance, app is the express app of your Parse Server
   let httpServer = require('http').createServer(app);
   httpServer.listen(port);
   var parseLiveQueryServer = ParseServer.createLiveQueryServer(httpServer);
   

2. Install Parse LiveQuery library as a pod to your project (pod 'ParseLiveQuery').

3. Subscribe for events:

   let myQuery = Message.query()!.where("user", equalTo: PFUser.currentUser()!)
   let subscription: Subscription<Message> = myQuery.subscribe()
   

4. Handle events:

   subscription.handleEvent { query, event in
       // Handle event
       // This callback gets called every time an object is created, updated, deleted etc.
   }