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Hey everyone welcome back.

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Johnny B here with slopes dot com.

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

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updating our chat B.C 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 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 web request we can take a look

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at it it is a get by request so we're just retrieving information and the header is a bear.

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So we we need to be logged in with an authorization token to access it and the new URL is a message

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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 the our m 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 oad right here

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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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Right.

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So we need the the user id and user 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 youll see here this time stamp will

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

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So let's 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 as a public private

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set ups not capitalize our message.

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And that's a strong hand.

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And I'm going to just copy this one to see

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and see how many are there.

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I'm an open post man and we need 1 2 3 4 5.

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One 8 1 2 3 4 6 7.

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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 tar Culloden

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ID and time stamp.

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See that is one.

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One two three four five six seven I guess it was only seven.

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Looks good.

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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 of request web request that emulates the postman

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

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So 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 are ill get messages

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find 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.

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All right.

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That's why I say find a 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 request

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and say channel Heidi.

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And that's going to be a string and then we're going to have her completion handler at completion at

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scaping

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and completion handler cause the bottom pane.

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Give us some room here.

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All right.

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Let's do this.

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Rinse the Alamo fire request and that says the request we want you are l is the one that we just created

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you are hell underscored get messages the method.

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Remember this one is a get.

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The parameters are.

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No 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 you go.

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And we want the response to come back in the form of a.

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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.

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Nice.

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

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That error is equal to.

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You know we're going to do something else.

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We are going to take completion is false.

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And then we are going to want to put the de-bug above that so we're going to debug.

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Print the errors when we say response that result.

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Dot error as any then we're going to see completion to false.

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But if we are successful then we are going to look through the object the jakes the objects in our response

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

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All of these then we're going to create a new message and then we're going to append it to an array

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of messages that we're going to create right here.

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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 out of 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.

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

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

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right here today.

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We're going to see phunk clear messages that's going to be messages that remove all that we go.

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And so right here we can actually clear the messages here.

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We're going to say sulf that clear messages.

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There you go.

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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 data into adjacent object using Swiftie Jaison.

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So when they say God hold it to equal the response that they tell else return and then we're going to

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say if let chase on equal to Jaison and we use the Swifty juice on initialiser right here and the data

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

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OK.

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Now we have an array of objects so now we're going to loop through we're going to see for item in chase

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on.

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So just like we saw in post man so this would be the case on 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 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.

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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 and this is going to be

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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 but Tiger 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 and this key is underscore ID the username key is user name the user Avatar

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key is user Avatar the user Avatar color key is user of our color and the time stamp key is time stamp

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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 message equal message with the struct initialiser and the message is message body.

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The username is a user name channel ID is channel I 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 timestamp is time stamp Whoy.

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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 is that

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append 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.

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I had to leave these spaces and Im going to save that and I think that that pretty much covers it that

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looks pretty good.

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So to test this lets go ahead and actually print the print this data out and say self that you are going

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to say 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 in D.C. actually because once we log in

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the 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 dot

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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 instance dot selected channel equal

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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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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 phunk 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 for an inside guard that channel ID equal message service

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instance does selected channel dot channel ID

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or Slik challenge that ID that we go.

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Else we 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 and the message service dot instance dot find all messages

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for Channel and the channel that we want to retrieve messages for our channel ID that we just unwrapped

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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 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 zero 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.

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So I have it inside of the for loop so I'm going to cut these two lines and these should actually be

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outside of the area.

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All right.

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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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Your will should also have appended at the end of it.

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The channel ID so going to do some string interpolation and say Your will get messages and then we also

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need to 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 because see here we have the Avatar color user names Emma the message hey Johnny

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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's swift to go and retrieve all of the messages for

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a 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 view based on that based on which channel is selected and

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that is where we created our new function from getting messages which goes and fetches the messages

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for a selected channel.

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So things are looking good.

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

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you 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.