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Hey everyone welcome back Johnny be here with slopes dot com.



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In the last lesson we worked on getting our log and flow set up and being able to select channels and



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updating our chat B.C.E. info a little bit and so we're going to continue on in that direction.



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And in this lesson we're actually going to write our functions to be able to fetch the messages stored



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on our API.



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And I know right now that you guys are going to have any messages on your servers yet because we haven't



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gotten to that point yet.



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But that's OK.



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I'll show you what the returning G song and everything will look like.



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So the first thing that we're going to need to do is know what our model needs to look like.



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So we open up postman and if you find the find all messages for channel a web request.



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We can take a look at it it is a get by request so we're just retrieving information and the header



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is a better header so we have we need to be logged in with an authorization token to access it and the



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URL is a message slash by channel and then the channel ID.



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All right.



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So if you check out your Mangu database here it's going to open up right here on our labs.



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So I'm in the I'm here in the collections are the channels collection and this shows our channels that



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we have.



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So you can see here we have the name of the channel just general the description and the oh Id right



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here that's the channel ID that we're going to be using in our app to has a unique identifier.



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All right.



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So and then that unique identifier is what we pass into the API request to retrieve the messages.



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And if I press send then this is what is returned.



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It's an array of J song objects in each chase object object or presents a chat message.



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And so the things that we need to account for in our model is the ID message body user ID channel ID



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user name user Avatar and Avatar color and the time stamp.



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So we need the the user id and use name and all that information to be able to you know make a clear



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indication of who it is that is sending the sending the message and you'll see here this time stamp



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will get to this later.



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The server returns it in a format that will have to convert later on.



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But but anyways.



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Yes so these are the properties of our model that we need to account for.



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So go ahead and create that model.



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We're going to come up here to model and say Right click on model group and say new file and this is



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going to be a swift file and we're going to call it message.



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I'm going to create it.



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All right and just like our channel this is going to be a struct structure and we call it message and



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we're just going to type out all of our properties of our structure that we need a public private set



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ups not capitalize our message.



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That's a strong hand.



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And then I'm going to just copy this one to see and see how many are there.



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I'm an open post man and we need one two three four five six seven eight.



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One two three four five six seven I think we need one more.



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All right and those are user name



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channel ID user Avatar



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user have a tar color



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I.D. and time stamp you see that I mean one.



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One two three four five six then I guess it's only seven.



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All right so now we have our model that will be able to use to save objects.



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All right so let's go ahead and now create the Alamo fire request web request that emulates the postman



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that we just saw and worked on that to do that we are going to need a u r l constant end point.



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Go ahead and open up our utilities and go to Constans and here under.



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You are always just going to copy this guy here paste it and this is going to be you or I'll get messages



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on the base you are l and then it is message slash by channel.



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I say that then let's go into our message service start swift and we were going to create a new function



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to get all messages right.



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That's when I say find her funk find all messages for Channel.



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OK.



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And we're going to pass into that a channel ID because that's what we need to be able to make the API



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requests and say channel Heidi and that's going to be a string and then we're going to have her completion



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handler at completion at scaping.



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That's and completion handler cause the bottom pane



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give us some room here.



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All right let's do this.



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Baranski Elmo fire request and this is the request we want the U R L is the one that we just created



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you are a hell underscore getting messages.



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The method.



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Remember this one is a gift.



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The parameters are no.



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We don't have a body to pass.



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The encoding is just on encoding that default and the headers we do need this to be a better header.



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There we go and we want the response to come back in the form of a song.



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Then offer the closure I'm going to press to return and change its name to response and encode and get



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rid of that.



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All right thanks.



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So now we're going to see if very spawn start result.



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That error is equal to nil.



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Never going to do something else.



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We are going to say completion is false and then we are going to want to put the debug above that so



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we're going to debug.



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Print the errors when I say response stop.



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Result.



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Error as any then we're going to set completion to false.



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But if we are successful then we are going to look through the object the joke's on the objects in our



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response and parse out the properties of a message that we need.



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All of these were meant to create a new message and now we're going to append it to an array of messages



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that were going to create right here so messages equal to an array of message and initialize.



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OK so we're only going to be storing the messages for one channel at a time.



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So once we select one channel we're going to load up the messages for that channel and then after and



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then if we select a different channel we're going to erase the messages the current messages and then



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replace that with the new channels messages to actually going to need a clear messages function right



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here today.



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We're going to see phunk clear messages.



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That's going to be messages that remove all that we go.



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So right here we can actually clear the messages here.



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We're going to say sulf that clear messages area and then we'll then world.



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Now we're going to go through the parsing parts when I say so remember the first step is to get the



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data and then turn that into adjacent object using Swiftie Jaison to miss it.



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Guard hold it.



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Data equal or response date time.



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Else return.



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And then we're going to say if let chase on equal to Jaison and we use the juice on initialiser right



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here and the data is the data that we just created and that is going to be of type array.



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OK now we have an array of Jasen objects so now we're going to loop through ruinously for item in chase



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on.



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So just like we saw in post man.



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So this would be the J song object that we just created.



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Now we're going to go through.



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We're going to see for each of these in it.



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Go through and extract the properties for each one.



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All right.



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So let's go ahead and do that.



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We're going to say let message body equal item and the key is called message body and that's going to



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be of type String about you.



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All right.



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And since there is quite a few of these I'm going to just kind of zip through.



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I'm going to copy and paste to the seven so one two three four five six seven.



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And this is going to be channel.



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Heidi this one's going to be ID.



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This is going to be user name.



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This one's going to be user have a tire.



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This is going to be user have a tar color.



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And this is going to be time stamp.



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Right now we got to go through and switch up all of the keys.



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So this key is channel ID.



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This key is under score ID the username key is user name the user Avatar key is user Avatar the user



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Avatar color key is user of our color and the time stamp key is time stamp all right there we go.



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So now we have all of the properties in variables that we need so we can create a new message I'm going



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to stay put message equal message with the struct initializers and the message is message body.



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The username is a user name channel ID is channel I d the user Avatar is used for Avatar use the Avatar



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color is user have a tar color.



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The ID is ID and the time stamp is time stamp duty.



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All right.



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So we are parsing through each individual item in J song.



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We are grabbing out the information and creating a new message object with that information and then



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we can append that new one that we just created two messages array and say self that message just append



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and the new element is that message that we just created.



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All right.



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And then we can see completion is true.



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All right go ahead.



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Delete these spaces and we're going to save that.



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And I think that that pretty much covers it that looks pretty good.



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So to test this let's go ahead and actually print the print this data and say self that going to say



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print self-taught messages.



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OK.



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And I say this and then we're going to jump over to our chat VC actually because once we log in the



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first thing we do is we go and we find all the channels right.



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So if we go and we get all of the channels there are either going to be no channels if is that like



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the very first time you have logged into the app and no one has created channels before.



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So there could be no channels or there could be some channels if there are no channels then we don't



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want to try and go and get messages because there's there's no channel there's no messages.



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All right so what we're going to do is we're going to do a check for that.



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We're going to see if message service dobbed



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instance that channels dot count is greater than zero.



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So we've logged in we've gotten all of our channels and if there are more than zero if there is at least



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one we're going to do is we're going to set the message service that instance does selected channel



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equal to the first one the message service in that instance that channels the zeroth item.



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So this is like if you have been logged in before and then you reenter the app and this is just going



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to by default set the first channel as the selected one.



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All right so we're going to say that and then we're going to say self-taught update with channel if



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there are no channels.



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We're going to go ahead and change our self channel name label that text to say no channels.



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Yes.



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OK.



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So we log in we find all of the channels if there's at least one channel then we set our selected channel



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equal to it and then we're going to update the channel then we're going to call this update with channel.



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So here an update with channel.



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What do we want to do.



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Well we're going to create a new function called get messages.



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And so this is where we call the function that we just created.



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So when I say funk get messages



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it here we're going to say we're going to call the function we need a channel ID.



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Right.



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So we're going to first unwrap that channel IDs.



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We're going to say guard let channel ID equal message service instance does selected channel dot channel



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ID



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or Slik child ID that we go.



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Else we're going to return.



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OK so now we have the channel ID the selected channel ID to create some space for us here.



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And now we can call the get the get messages functions from and say Message Service that instance dot



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find all messages for Channel and the channel that we want to retrieve messages for our channel ID that



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we just unwrapped completion.



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I'm going to change to success.



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And right now we're not doing anything with that information.



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But let's put our get messages function right here and update with channel so get messages.



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And that should that should work for us.



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So I'm going to run this.



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And while it's coming up I'm going to walk you through the flow once again.



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All right.



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So we logon we do our find all channel function which returns an array of functions.



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If there's at least one function then we are going to set the selected channel equal to the zeroth channel



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then we're going to update with channel.



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What that does is we set our channel name and we try to and we attempt to get messages when we attempt



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to get messages we are getting the channel ID from our selected channel and then we're passing that



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in to find a message for a channel where we look through if there are any if there are any messages



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then we loop through and extract the information that we need and then create new message objects and



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add them to our messages rate and message service.



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And so we said to print it out so let's see if we got anything here.



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You know what.



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I accidentally put the completion in the wrong place so I have it inside of the for loop.



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So I'm going to cut these two lines and these should actually be outside of the area.



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All right so let's try that again.



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OK.



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So that wasn't the only mistake I made.



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I made a rather large one right here.



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You're all that we need to ping is not just is not just this right.



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The Tauriel should also have appended at the end of it the channel ID.



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So we're going to do some string interpolation and say your l get messages and then we also need to



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tack onto it the channel ID string that we have passed into it.



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So I want to say channel Heidi.



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There we go.



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Save that and run.



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All right.



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So third time's the charm.



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Finally we are seeing the message data that is being printed out.



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So that is that is good to see here we have your avatar color user names Emma the message.



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Hey Johnny what's going on.



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So yeah it's working out well.



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So just to recap what we did in this lesson we created a model for the messages.



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We created a function in our message service that swift to go and retrieve all of the messages for a



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given channel.



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Then in our chat Visi we did a little bit of work and created a few more functions so that when we log



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in we do a check for any check for more than one channel.



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We select a channel and then we update the the view based on that based on which channel is selected



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and that is where we created our new function.



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We get messages which goes and fetches the messages for a selected channel right.



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So things are looking good.



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Probably guys are having fun and in the next lesson we're going to work on adding messages so that you



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guys can actually see something be returned with that function.



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And yes so we're we're making great progress.



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And I'm going to finish up here by adding and committing our changes and then I'll see you guys in the



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next one.