HRESULT XStoreShowPurchaseUIAsync(  
         const XStoreContextHandle storeContextHandle,  
         const char* storeId,  
         const char* name,  
         const char* extendedJsonData,  
         XAsyncBlock* async  
)  

void CALLBACK ShowPurchaseUICallback(XAsyncBlock* asyncBlock)
{
    HRESULT hr = XStoreShowPurchaseUIResult(asyncBlock);

    if (FAILED(hr))
    {
        printf("Failed the purchase: 0x%x\r\n", hr);
        return;
    }
}

void ShowPurchaseUI(XStoreContextHandle storeContextHandle, XTaskQueueHandle taskQueueHandle, const char* storeId)
{
    auto asyncBlock = std::make_unique<XAsyncBlock>();
    ZeroMemory(asyncBlock.get(), sizeof(*asyncBlock));
    asyncBlock->queue = taskQueueHandle;
    asyncBlock->callback = ShowPurchaseUICallback;

    HRESULT hr = XStoreShowPurchaseUIAsync(
        storeContextHandle,
        storeId,
        nullptr,    // Can be used to override the title bar text
        nullptr,    // Can be used to provide extra details to purchase
        asyncBlock.get());

    if (FAILED(hr))
    {
        printf("Failed to purchase: 0x%x\r\n", hr);
        return;
    }
}