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Hey everybody what's going on this is Caleb with slopes dot com and get excited because we're going

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to dive into the world of in-app purchases in this video by creating our IAP service singleton class.

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So pull open your X code project and let's go ahead and let's right click on food Zilah.

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Let's create a new group called services and we're going to then right click and create a new file.

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This is where we're going to create our IP service.

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So go ahead and click on swift file.

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Go ahead and write.

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Service like so and create it.

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Now a singleton class is a class that is basically like you instantiated on itself and that allows it

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to be used throughout the entire life cycle of the application it's really neat.

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It's a really cool way to access any in class and like settle the values in you know access all the

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functions and do all kinds of cool stuff from any other class in your app.

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But the singleton pattern can be abused.

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So we're going to do our best not to do that but go ahead and create a class called IAP service and

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go ahead and create a constant called Let instance equals IAP service and we're going to instantiate

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it from the get go.

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Now in order for a singleton class to work you have to actually declare the instance as static and all

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that static means is that the instance of IAP service is going to be accessible throughout the entire

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duration of the app lifecycle.

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So it's not going to be deallocated or initialized or anything because it is static it means it stays

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there it stays in place.

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So that's why we're going to use static to create our singleton.

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Now when we want to access this we could say you know let blaw equal IAP service instance.

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And now inside of instance we can access all the properties that we could for any normal class and you'll

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see how that works later on.

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But for now before we move on we actually need to go ahead and import a framework here.

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So go ahead an import store kit like so and that's going to give us access to all the Inet purchased

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goodness.

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All right.

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And then what we need to do actually is we need to conform to S-K product request delegate.

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So this is going to be conforming to S-K product request delegate now S-K stands for store kit and the

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S-K product request delegate allows us to request products but it's saying that this does not conform

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to the protocol and as object protocol.

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And that is because when you're using store kit you also need to conform to can't type and hence object.

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So go ahead and type that.

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And when you build and run you'll notice that it now only tells us that we don't conform to the S-K

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product request delegate and that's because we have not yet basically used our S-K product request delegate

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methods that are required.

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And the first one is product request.

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OK.

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Sorry you should read that description here accepts the response from the App Store that contains the

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requested product information.

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OK.

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And go ahead and press enter.

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Now.

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Product request did receive response.

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Now that is the function that we need in order to actually conform to S-K product requests delegate.

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But like it said it's going to basically accept the response from the App Store but we need to first

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set up you know how are we actually going to do that.

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And so let's begin by writing a function here called load products and load products is going to do

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two things.

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It's basically going to take all of our product IDs and convert them into a set of type string.

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Then we're going to go ahead and call request product which we have not written yet.

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But what that's going to do is it's going to make an S-K product request and passed that set of strings.

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The set of IDS up to iTunes to check hey is it legit.

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Is it really connected with this project and it will return to us some information.

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Then after we request all those products what we're going to do is we're going to set those products

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to live in an array in our IAP service and we're going to pass that array in to our products requester

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it will make more sense as we go about it.

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So let's go ahead and let's do that now in order to begin we're going to be calling a function here

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called Product ID to string set.

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Okay that's one function that's going to convert all of our IDs to a string set and you're probably

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saying wait what ids are you talking about.

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Do you remember when we set up iTunes Connect.

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We created a product ID.

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OK AP course meal.

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Now is the time we're going to use that.

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So copy it from iTunes Connect or just remember it.

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And we need to set up a constant file and this constant file is basically going to give us access similar

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to our food items on a wide scope.

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So go ahead and right click Create a new group and call it.

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Oh you know what.

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This could go on our helpers.

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So let's go ahead and get rid of that group.

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Bye bye.

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And in helper's right click new file swift file and call it Constance OK create it.

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And now we're going to go ahead and just call this.

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Let IAP underscore meal ID.

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OK.

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And let's set that to Comcast AP course meal.

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Now we can use that.

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We don't have to type this as a string ever again which is really nice.

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We can't really you know mistyped it.

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So back to our IP service.

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We are going to use the product ID and convert it into a set of string because that's what that's what

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iTunes actually requires us to use is a set of string.

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So let's think after we convert all of the IDs into a set of strings we need to go ahead and call request

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products which is another function we're going to write but we're going to pass in those product IDs

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that we generate.

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OK.

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Or I guess the set of string from the IDs and request products is going to make that Eskay product request

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pass it in send it up to iTunes they'll send back saying yep you're good or no you're not good.

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And that's where products requested receive response is going to get called.

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So let's go ahead and let's build out these two functions first and then we're going to go ahead and

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you know uncommented them and make sure they work.

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So go ahead and let's call phunk product ID to string set like so without the capital-T there and now

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what we're going to do is we're going to take our identifier.

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Right.

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IAP M.D. and we're going to need to pass that in to a set of type string.

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So let's go ahead and let's create a variable at the top called product IDs and we'll make it of type

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set and string.

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So var product IDs it's going to be equal to a set K which is a collection type and it's going to be

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of type string.

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Now instantiate it from the beginning and all we need to do now is we're going to go ahead and call

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product IDs insert and look at that we can insert a new member just like that.

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So go ahead and call insert and we're going to go ahead and insert IAP Meehl ID.

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And now we have a set of type string with our melody good to go up to iTunes.

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OK that's easy.

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We just converted it into a string set.

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Next we're going to go ahead and write our function here called request products.

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So go ahead and type phunk request products.

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And we're going to need to pass in a set of type string.

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So let's go ahead and let's pass in let's see requests products for IDs and we'll just use an internal

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parameter there of IDs that's going to be of type set with the internal set or internal type of string.

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So there's that function.

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Now what are we going to do.

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We need an instance of S-K product request so let's go ahead and create that var product request.

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It's going to be equal to S.K. product request and go ahead and instantiate it.

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So there we go we've got a product request.

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Now we need to call some particular functions on it to set it up.

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So go ahead and say product request is equal to S-K product request and we're going to instantiate it

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fully now.

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Now look at that.

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It asks for a set of string of product identifiers.

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Press enter and pass it on IDS.

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Beautiful.

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After that we can go ahead and set the product request delegate to be equal to self thanks to us already

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conforming to it.

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So go ahead and call products request delegate equals self and then beneath that we need to call a function

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that's going to start the process like we've loaded up the data.

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Now we need to actually start sending it up to iTunes and waiting for a response so go ahead and call

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product request that start and it sends the request to the Apple store.

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But what if we started this and then got stuck halfway through and tried to request it again that would

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not be good.

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So in order to safeguard ourselves we were going to call product requests cancel at the beginning so

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that if there is a product request we will cancel it first and then start a new ones.

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We don't have an issue of multiple requests going on at the same time.

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So now that we have this good to go we're going to go ahead and uncomment.

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Well uncomment these and just like that is going to let us pass him in although we're missing a parameter

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here of IDS or I guess it's for IDs right for IDS build and run make sure that it's good to go.

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Or I guess just build K cool.

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So what we're doing here load products converts our product ID into a set of type String request products

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is basically passing in that set.

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Uploading it to iTunes and then as soon as we get a response from the server this function product request

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gets called.

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So what we need to do is we need to set up an array of type S-K product because inside of an S-K product's

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response we get all of those products back from iTunes.

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So let's go ahead let's set that up here.

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Var products.

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And that's going to be equal to an array of S-K product.

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Now let's instantiate it from the beginning.

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So it at least has an empty value.

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And what we're going to do is we're going to set self up products to be equal to response because remember

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it's S-K product response and watch this response dot products.

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We get an array of S-K product.

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Super awesome.

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Now let's say that we got zero products what if zero products came back.

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So if so if products count is equal to zero meaning of zero products come back we're going to go ahead

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and call request request products for IDs and we're going to send in the product IDs.

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So this is sort of like a retry.

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Right if it comes back empty like if the server doesn't work it's going to retry until we get all of

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our items that we need.

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OK but if it worked if we get all of our products back we're going to call.

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Else.

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And this is where we need to basically inform our app that all of our in-app purchases were downloaded.

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And so this is where we're going to use a protocol that's going to be a really easy way to help us basically

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pass data between two controllers using delegation.

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So in order to do this go up to the top of IAP service and type protocol IAP service delegate.

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And inside of this we're going to set up a function.

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We're not going to give any functionality because that happens wherever this delegate is conformed to.

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But for now just go ahead and call phunk IAP products loaded and give it the parentheses needed to declare

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it as a function.

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And now we have a protocol that's going to allow us to pass information to another view controller when

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all the products are loaded.

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So go ahead.

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And what we're going to do is create a property to hold an instance of delegate and go ahead and do

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that by typing var delegate equals are not equal sorry of type IAP service delegate.

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And set it to be optional.

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Because from the beginning if we were not going to instantiate it we don't actually have it unless it's

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being conform to somewhere else.

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But assuming that it's being conformed to we can call delegate dot and check it out.

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We can say products loaded.

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So if we have conformed to this delegate and another view controller we can call this function and then

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on that controller that function will load.

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That's the cool thing about delegation is that another class can control another class.

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Pretty cool.

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So let's go ahead and in storefront Visi Let's actually conform to that delegate and then set up a function

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to basically tell us hey everything's loaded.

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You're good to go.

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So to do that let's go ahead and let's create actually an extension beneath our class and let's type

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extension

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storefront Visi and we're going to go ahead and conform to IP service.

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We don't have access to it yet.

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Build the project service delegate.

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Boom.

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Now if I build it it's going to say hey you don't conform to a service delegate.

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That's because we have not called IAP products loaded.

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OK.

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So basically in our IAP service if everything loads the way that it's supposed to we can call delegate

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IAP products loaded and it's going to call that function here.

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So we're going to just print saying IAP products products loaded.

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And that's only going to get called if it actually works which is cool.

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So now how do we set.

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How do we set this view controller to actually be the the delegate.

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How do we set it up so that it knows that this view controller particularly is the delegate super easy.

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All we need to do is access our IP service class and set the delegate to be this view controller because

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we've already conformed to it.

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So go ahead and in your view to load call IAP service instance and now check it out.

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We have access to all those functions and all those properties but we just care about the delegate.

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So IP service that instance delegate is equal to self or this controller.

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Then all we need to do in order to actually load up our products is call IAP service instance load products.

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It's that easy when we do that.

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It's going to go ahead and convert it request the products and when it's requested it's going to go

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ahead and check if 0 came back at all request again if they all came back.

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It will call IP products loaded meaning we have all of our products and it worked.

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So I don't know about you but I really want to go test this to see if it worked.

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Go ahead and click build and run.

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And we're going to pull up our simulator here and we're going to see if our labor was worth it if what

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we did worked we should get a nice print out in the console if all of our IP products came back the

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way they were supposed to so it's going to go ahead and build and run.

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Do do do.

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And look at that it printed IP products loaded but you know what I want to prove it.

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So go ahead and click on IP service and what we're going to do is we're actually going to let's let's

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print out let's print Let's go into the products array and let's just print out the first item and we

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should be able to access the localized title which I think should be meal.

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Let's build and run it again and let's see if it actually does download those pieces of data from iTunes

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the way that we expect

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boom.

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Can you see that it says meal right there.

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That's from iTunes.

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That's the one that we set.

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We have not type that anywhere in this application so we are officially downloading that information

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from Apple from IP services.

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And this is working guys this is amazing.

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So now believe it or not we have access to all of our in-app purchases.

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We're going to do some more things to continue building this out and making it even more amazing.

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But guys seriously we are so much closer to making real in-app purchases in our in our app.

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We can download all of our purchased products and now we can start setting them up to be able to be

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purchased.

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So let's head over to the next video where we're going to continue building this out and diving into

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the world of consumables.