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What are Choosers in Windows Phone?
Launchers are API in Windows Phone that allows the users to perform some common task like Launchers.
The difference between a Launcher and a Chooser is that Launchers do not return any data back to your App whereas the chooser returns data back to your app.
Example of a choosers is opening the list of Phone Contacts and selecting one and getting it back to the App.
Some of the Choosers include