Launchers and Choosers enable the Windows Phone applications to access the built-in applications and data stores on the device. For example, if we want to make a phone call from within our application, we would use what we call a Launcher; or if we want to access the data libraries on the device, such as the photo library, we would use what we call a Chooser.
The main difference between a Launcher and a Chooser is that Launchers don't return any value, whereas Choosers return a value. For example, we have a Launcher known as EmailComposerTask
that starts the e-mail application and when it exits, the control is returned to the application that called it. We also have a Chooser called CameraCaptureTask
that starts the camera application. After the user takes a picture, the camera application exits and returns the value of the photo that was taken.
When we call a Launcher or a Chooser, our Windows Phone application goes to the background, and the built-in application...