1. App Group
You do have the support of accessing and communicate between applications if the applications are in the same App Group.
Each application when is running in a separate process, even if the applications are part of the same App Group,
they do not access each other's directories, but they have access to the Shared Container that has a Sandbox-like directory structure, that looks like in the image below:
First of all, you need to create an App Group for your application. Go to Apple Developer Member Center and register App Group. Fill the description and identifier and follow the instructions.
After that when you will create an identifier for an application or an extension, don’t forget to enable the service App Groups.
Then go to the application or the extension and edit services. It’s really simple, see the next screenshots:
It’s all settings, now open the Xcode and let’s go to write code. In the Xcode for the each target enable App Groups in target settings.
And please, perform this procedure for all applications or extensions of the App Group.