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It's time to start implementing Firebase in Fury, and we're going to do all of this inside of The View



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controller.



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Now, if you are making a production app, a commercial app of some sort, then you probably want to



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abstract the firebase stuff away into its own class and then listen to that class from the particular



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view controller you're looking at for two reasons.



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One, so it's maintainable, you know what you're changing and where.



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And two, you don't confuse your view controller code or have to repeat your code when you create another



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view controller that displays the data slightly differently.



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You just want to access one class for your data.



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OK, so we are not going to reinvent the wheel.



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We're going to look at the way that I've done this before.



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So we need, first of all, to declare three objects.



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The first object is a variable for messages and we're going to get a data snapshot array from Firebase.



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That's a snapshot of the data.



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At a particular point in time, we are going to get a database reference from Firebase.



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That's pretty self-explanatory.



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And we're going to get a database handle on the database objects so we can go and access that database



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whenever we need to.



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OK, and that's giving us an error because we need to import these two items because we only have Firebase



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Auth in here right now.



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OK, so we've got our database ready to go now.



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We need to go and set that up.



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So the first thing that we're going to do is create a method called a set up firebase.



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So I'm just going to copy this straight over.



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Just below did load and then I'm going to call that down here now, in the end, this might have an



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effect on our UI because we're checking the user and setting up Firebase.



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We might want to set up Firebase only if the current user is logged in.



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So that's a problem we can fix later on.



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But for now, our app is set up, so our user is always logged in.



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OK, so we can worry about that little bug later on.



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And I only know that's a bug because when I was preparing the update for this course, I discovered



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my own bug.



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Right.



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So in our set up firebase and post this, if you need to copy the code, we have that reference which



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we get from the FIREBASE database object.



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And the current instance of that object is here.



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And then we grab the reference of that.



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Then we have a reference handle on a particular part of that database.



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So we need the ref for that.



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And we tell it, I want you to go and look at the child called messages.



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So in the firebase database.



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And I don't think I actually have any here.



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Not yet anyway.



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We are going to have a sub child called messages now.



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Important distinction if you've done SQL database before or any kind of databases.



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Firebase is based on a document database like Mongo, for example.



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In fact, I think it does use Mongar, but don't quote me on that.



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That is different to how we structure other databases.



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So don't think of a child as a table.



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It's not a table of messages, it's just a subcategory.



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The subcategories are very, very limited in the number of them you can implement in Firebase.



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So don't arrange your data that way.



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I'm doing that here.



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So our app looks clear.



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A lot of people would be tempted to go, you know, create a table for messages, create a table for



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messages between these two people and these two people and these two people.



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And you could see how that's going to expand crazily over time.



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So you don't want to do it like that.



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Instead, in the table of messages, you put everybody's message, you get your authentication rules



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right so everyone can access everyone else's messages just their own.



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And what's the final thing you have to do?



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If you want to categorize the messages, you add an object into each message document so we know what



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category that's in.



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So that's just a warning for you from someone who's done it the wrong way before.



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Then what do we do?



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We're going to add an observer, so whenever this changes, Firebase will pay us a message and say it's



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changed.



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What kind of things are we going to listen to or we're only going to listen to?



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Child added as in someone's added a new message to the stack.



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Now, of course, you can customize this because you don't want everyone to be listening for a child



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added when it's a private conversation between two people.



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I'm just doing this quick and dirty for us so we can understand what's going on.



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But you can, of course, customize that.



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There are other ways.



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Child added, child change, child moved, a child removed.



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OK, so lots of things you can listen to.



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Then if that event fires off, it's going to return a data snapshot from Firebase.



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At that point, we're going to get that data snapshot and add it to our messages object.



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Now, this is only going to give us the difference, it's not going to send over the whole data table,



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if you like, it's just going to send us the difference.



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The one that was added, if you have if you're listening to something like child changed, then you're



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going to have to have a method that finds that one in your list of messages replaces it with the new



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data.



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OK, so that's just a warning.



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But what we're doing here is just appending because it's the easiest way of doing things and showing



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you and keeping you interested, then what we're going to do is go to the table view and we're going



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to insert a row at the current index paff.



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End.



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OK, so this code gets the index path and it finds the end cell and we do the minus one because of the



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zero based indexing there and it inserts that particular row.



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OK, and then down here is just a nice little thing.



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You don't need it, but it will automatically scroll the table up to the end of that row.



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So when you get a message, just like in a message or WhatsApp, it scrolls to the bottom automatically.



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OK, so that's just a nice little thing now.



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So we've we've set up Firebase.



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We've got all that reference.



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Currently, there is no data in Firebase.



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So what I'm going to do is, first of all, actually scrolling down the code, we're not going to see



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anything away because the table view just has 100 items and the table view just returns a bog standard.



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So we haven't changed it yet.



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So let's return the number of rows in section.



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Let's see what I put in the code here.



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Just the messages don't count.



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OK, and that will automatically update if we have more messages.



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Now, I'm going to copy this code that's going to implement our cell faurot act.



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So feel free to pause and copy this code.



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Right, so first of all, we're going to grab the message, then we're going to get the message content



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from the FIREBASE database as a dictionary of string and string.



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That's just how it comes out.



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Then we say, if you can get some text from those message fields, what message fields?



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Well, we haven't actually set that up, so that's what we should do now.



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We should have constant stop message fields set up.



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And in my other code here, here we have it.



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So I'm just going to copy this, paste it and explain.



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All I'm doing is setting a file with some constants so we don't mess up what things are called.



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So it's going to go, hey, if I want the date time, it knows to use the string.



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If I want the text, it knows to use this string.



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And these are the fields that we're going to use in Firebase to define the data that we're going to



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pull through.



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So once I've put that in, our silly error should go away here.



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You can find it, oh, I know you can.



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What if I press play it should find it then.



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Yeah, there we go.



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It's found it.



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Yes, it has.



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OK, so that's of doing, going and building itself and where we have our app again with an empty list,



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because it's pulled nothing down from Firebase yet.



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But if I insert some dummy data, then we're going to see some messages coming through.