Auto-launching apps in Windows phone

You can use file and URI associations in Windows Phone 8 to automatically launch your app when another app launches a specific file type or URI scheme. When launched, a deep link URI is used to send the file (a reference to the file) or URI to your app. You can also use the association launching API to launch another app in the same way. This topic describes file and URI associations, and how you can use them in your app.

File associations

File associations allow your app to automatically launch when the user wants to open a particular file. That file could come from a variety of sources including, but not limited to:

• an email attachment
• a website via Internet Explorer
• a Near Field Communications (NFC) tag
• another app from the Store

To register for a file association, you must edit WMAppManifest.xml using the XML (Text) Editor. In Solution Explorer, right-click the WMAppManifest.xml file, and then click Open With. In the Open With window, selectXML(Text) Editor, and then click OK.

XAML

<Extensions>
   <FileTypeAssociation Name="Windows Phone SDK test file type" TaskID="_default" NavUriFragment="fileToken=%s">
       <Logos>
           <Logo Size="small" IsRelative="true">Assets/sdk-small-33x33.png</Logo>
           <Logo Size="medium" IsRelative="true">Assets/sdk-medium-69x69.png</Logo>
           <Logo Size="large" IsRelative="true">Assets/sdk-large-176x176.png</Logo>
       </Logos>
       <SupportedFileTypes>
         <FileType ContentType="application/sdk">.sdkTest1</FileType>
         <FileType ContentType="application/sdk">.sdkTest2</FileType>

       </SupportedFileTypes>
   </FileTypeAssociation></Extensions>

Listening for a file launch

When your app is launched to handle a particular file type, a deep link URI is used to take the user to your app. Within the URI, the FileTypeAssociation string designates that the source of the URI is a file association and the fileToken parameter contains the file token. For example, the following code shows a deep link URI from a file association.

namespace sdkAutoLaunch
{
    class AssociationUriMapper : UriMapperBase
    {
        private string tempUri;

        public override Uri MapUri(Uri uri)
        {
            tempUri = uri.ToString();

            // File association launch
            if (tempUri.Contains("/FileTypeAssociation"))
            {
                // Get the file ID (after "fileToken=").
                int fileIDIndex = tempUri.IndexOf("fileToken=") + 10;
                string fileID = tempUri.Substring(fileIDIndex);

                // Get the file name.
                string incomingFileName =
                    SharedStorageAccessManager.GetSharedFileName(fileID);

                // Get the file extension.
                string incomingFileType = Path.GetExtension(incomingFileName);

                // Map the .sdkTest1 and .sdkTest2 files to different pages.
                switch (incomingFileType)
                {
                    case ".sdkTest1":
                        return new Uri("/sdkTest1Page.xaml?fileToken=" + fileID, UriKind.Relative);
                    case ".sdkTest2":
                        return new Uri("/sdkTest2Page.xaml?fileToken=" + fileID, UriKind.Relative);
                    default:
                        return new Uri("/MainPage.xaml", UriKind.Relative);
                }
            }
            // Otherwise perform normal launch.
            return uri;
        }
    }
}

more info :

http://msdn.microsoft.com/library/windows/apps/jj206987(v=vs.105).aspx

Enjoy!