Wait for chain of tasks

Question

I am working with the Magazine sample app for using DirectWrite from a XAML-based app. It has a FontLoader class, which has the LoadAsync method, which does something like this:

void FontLoader::LoadAsync()
{
    // Locate the "fonts" sub-folder within the document folder
    task<StorageFolder^> getFolder(m_location->GetFolderAsync("Fonts"));
    getFolder.then([=](StorageFolder^ folder)
    {
        // Enumerate a list of .TTF files in the storage location
        auto filters = ref new Platform::Collections::Vector<Platform::String^>();
        filters->Append(".ttf");

        auto queryOptions = ref new QueryOptions(CommonFileQuery::DefaultQuery, filters);
        auto queryResult = folder->CreateFileQueryWithOptions(queryOptions);

        return queryResult->GetFilesAsync();

    }).then([=](IVectorView<StorageFile^>^ files)
    {
        // Here is some more async processing code.
    });
}

How can I make a Sync version of this method and wait for the whole chain to finish? I basically want to wait until all the async tasks here (also the tasks inside the second continuation) are completed.

I tried to call getFolder.wait() at the end of the function, but that threw an exception.

Thanks.

Answer 1

Dear Mark

I had a same problem with you and look forward somebody to answer it.

Answer 2

Hello,

If you call the getFolder.wait();. It only run the function getFolder not the getFolder.then().

I suggest you to use .wait() at the end of then() like:
getFolder.then().then().wait();

Also, you can use .wait() inside the
then([=](IVectorView<StorageFile^>^ files)
    {
        // Here is some more async processing code.
    });

For more information, please check
http://msdn.microsoft.com/en-us/library/windows/apps/dd492427(v=vs.110).aspx

Best regards,
Jesse

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Jesse Jiang [MSFT]
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