The DataTransferManager class includes a ShowShareUI method, which you can use to programmatically start a share operation. In general, we recommend against using this method. Users expect to initiate share operations by using the Share charm—when you launch the operation programmatically, you can create an inconsistent user experience. We include the method because there are a few scenarios in which the user might not recognize opportunities to share. A good example is when the user achieves a high score in a game.
The DataTransferManager class also has a TargetApplicationChosen event. Use this event when you want to capture what applications a user selects when sharing content from your app.