in app purchase with #win8dev #winrt

Windows 8 – WinRT API exposes few classes that make implementing #IAP a simple task. In additional it provides simulator class that makes testing the functionality easy.

The store related functionality is exposed by the following classes

CurrentApp class	Defines methods and properties you can use to get license and listing info about the current app and perform in-app purchases.
CurrentAppSimulator class	Defines methods and properties used to instantiate an object that you can  use to get simulated license info during testing.
LicenseInformation class	Provides access to the current app’s license metadata.
ListingInformation class	Provides the listing info that describes the app in the Windows Store.
ProductLicense class	Provides info about a license that is associated with an in-app offer.
ProductListing class	Provides localized info about an  in-app offer in your app.

To test the code in simulator, you need to load some data is. I used in-app-purchase.xml like in the store sample – it looks like this

<?xml version="1.0" encoding="utf-16" ?>
<CurrentApp>
  <ListingInformation>
    <App>
      <AppId>988b90e4-5d4d-4dea-99d0-e423e414ffbc</AppId>
      <LinkUri>http://apps.microsoft.com/webpdp/app/988b90e4-5d4d-4dea-99d0-e423e414ffbc</LinkUri>
      <CurrentMarket>en-us</CurrentMarket>
      <AgeRating>3</AgeRating>
      <MarketData xml:lang="en-us">
        <Name>In-app purchases</Name>
        <Description>AppDescription</Description>
        <Price>0.00</Price>
        <CurrencySymbol>$</CurrencySymbol>
        <CurrencyCode>USD</CurrencyCode>
      </MarketData>
    </App>
    <Product ProductId="SingleChar1Hint">
      <MarketData xml:lang="en-us">
        <Name>SingleChar1Hint</Name>
        <Price>0.99</Price>
        <CurrencySymbol>$</CurrencySymbol>
        <CurrencyCode>USD</CurrencyCode>
      </MarketData>
    </Product>
    <Product ProductId="SingleChar2Hint">
      <MarketData xml:lang="en-us">
        <Name>SingleChar2Hint</Name>
        <Price>0.99</Price>
        <CurrencySymbol>$</CurrencySymbol>
        <CurrencyCode>USD</CurrencyCode>
      </MarketData>
    </Product>
    <Product ProductId="DoubleCharHint">
      <MarketData xml:lang="en-us">
        <Name>DoubleCharHint</Name>
        <Price>1.29</Price>
        <CurrencySymbol>$</CurrencySymbol>
        <CurrencyCode>USD</CurrencyCode>
      </MarketData>
    </Product>
    <Product ProductId="AdFree">
      <MarketData xml:lang="en-us">
        <Name>AdFree</Name>
        <Price>0.99</Price>
        <CurrencySymbol>$</CurrencySymbol>
        <CurrencyCode>USD</CurrencyCode>
      </MarketData>
    </Product>
  </ListingInformation>
  <LicenseInformation>
    <App>
      <IsActive>true</IsActive>
      <IsTrial>false</IsTrial>
    </App>
    <Product ProductId="SingleChar1Hint">
      <IsActive>false</IsActive>
    </Product>
    <Product ProductId="SingleChar2Hint">
      <IsActive>false</IsActive>
    </Product>
    <Product ProductId="DoubleCharHint">
      <IsActive>true</IsActive>
    </Product>
    <Product ProductId="AdFree">
      <IsActive>true</IsActive>
    </Product>
  </LicenseInformation>
</CurrentApp>

In the app initialisation code, I tend to load this data into the CurrentAppSimulator.

#if DEBUG
    StorageFolder proxyDataFolder = await Package.Current.InstalledLocation.GetFolderAsync("Assets");
    StorageFile proxyFile = await proxyDataFolder.GetFileAsync("in-app-purchase.xml");
    await CurrentAppSimulator.ReloadSimulatorAsync(proxyFile);
#endif 

as you can see I use compiler preprocessing directive to make sure only debug code uses CurrentAppSimulator and the dummy IAP pricing data. Once the data is loaded, you can use CurrentAppSimulator like you CurrentApp class. Lets have a look further. I continue with compiler directives through out..
In the Page loaded event handler, I check to see if I need to show any particular IAP option

#if DEBUG
    LicenseInformation licenseInformation = CurrentAppSimulator.LicenseInformation;
    ListingInformation productListing = await CurrentAppSimulator.LoadListingInformationAsync();
#else
    LicenseInformation licenseInformation = CurrentApp.LicenseInformation;
    ListingInformation  productListing = await CurrentApp.LoadListingInformationAsync();
#endif

    var adFreeIAPListing = productListing.ProductListings["AdFree"];
    this.spAdFree.Visibility = (bAdFree ? Windows.UI.Xaml.Visibility.Collapsed : Windows.UI.Xaml.Visibility.Visible);
    this.tbAdFree.Text = String.Format("buy for {0}", adFreeIAPListing.FormattedPrice);

the buy button itself is in stackpanel called spAdFree. Lets look at the IAP handling code

#if DEBUG
    await CurrentAppSimulator.RequestProductPurchaseAsync("AdFree", false);
#else
    await CurrentApp.RequestProductPurchaseAsync("AdFree", false);
#endif
    if (AdFreeChanged != null)
        AdFreeChanged();

The AdFreeChanged in an event I expose to toggle main page’s ad control. The IAP is shown in Settings Flyout. If you have any questions, drop me a message