Application instancing
As we mentioned in the previous section, UWP apps use, by default, a single-instancing model. If you have an instance of the application running and you try to open a new one using a different activation path (for example, you have double-clicked on an associated file type in File Explorer), the already running instance will be reused. Starting from Windows 10 1803, UWP applications have also gained support for multi-instancing, but this is an opt-in feature.
In the Win32 ecosystem and, as such, in the Windows App SDK as well, the default approach is instead the opposite one: by default, different activation paths will lead to multiple instances of the application being opened.
This behavior is the most flexible one since it enhances the multitasking capabilities of your application. However, there might be scenarios in which you would like to keep using the single-instance model. This is possible thanks to the AppInstance class that we introduced in the...
