Installation for macOS is the same as for iOS, however, there is one small extra step.
The Sandbox on macOS
You do not need to perform any of these steps for an application running on iOS, or if your macOS application is not sandboxed.
Currently, use of ObjectBox from a sandboxed macOS application requires you to set up at least one App Group for ObjectBox to be able to open a database, in addition to whatever you would normally have done to gain access to the destination folder under the sandbox:
Open your project in Xcode.
Select the project icon at the very top of the Project Navigator.
Select the Signing & Capabilities tab where you turned on App Sandbox.
Click the + Capability button and double-click App Groups.
If the App Groups list is empty, click the little "+" icon to add one.
You should now see a list entry like FGDTDLOBXDJ.$(TeamIdentifierPrefix). If you only see $(TeamIdentifierPrefix) , you still need to set up your team and code-signing under General.
That should be it: ObjectBox will pick up the App Group Identifier without any additional work.
Pick a short group identifier. There's an internal limit in macOS of 31 characters for semaphores, that enforces the complete string (FGDTDLOBXDJ.$(TeamIdentifierPrefix) in the example) to be 20 characters or less.