Since the release of Windows Phone SDK 7.1 RTM , when we create a new project in Visual Studio 2010 Express for Windows Phone, we can choose the OS version. The options include 7.0 and 7.1. The default is 7.1, as shown in Figure 1 below:
Figure 1: OS selection interface when creating a new project
Then, for the previous application project, if you want to update to a new OS version, the operation is also very convenient. Below we will give the operation steps in order. Take the source code of Chapter 27 in "101.Windows.Phone.7.Apps, Volume.I" as an example, use Visual Studio 2010 Express for Windows Phone to open the Groceries.sln file, as shown in Figure 2 below:
Figure 2: Open the application interface
In the resource browser of the project, right-click the project of the project, as shown in Figure 3 below, the right-click menu will pop up, and click "Upgrate to Windows Phone 7.1"
Figure 3: Project right-click menu
After that, a prompt message box pops up in the development environment to remind the user that any other projects referenced in the project will not be updated, as shown in Figure 4 below.
Figure 4: Project upgrade reminder
After the upgrade is completed, compile, the system prompts missing components:
The referenced component'Microsoft.Phone.Controls.Toolkit' could not be found.
We know that the above warning is due to the fact that Silverlight for Windows Phone Tookit is not installed. Currently, the toolkit has been updated to the latest November 2011 version (for OS7.1). You can download it here: URL . As shown in Figure 5 below:
Figure 5: Silverlight for Windows Phone Tookit
After installation, we delete the old references in the project references, and manually add new references, as shown in Figure 6 below:
Figure 6: Delete the old reference
The new dll path is located at: %\Program Files\Microsoft SDKs\Windows Phone\v7.1\Toolkit\Oct11\Bin, the interface for adding a reference is shown in Figure 7 below:
Figure 7: Adding a new reference
At this point, the project can be compiled and debugged.