Recently I worked on a project that uses Core Data. The underlying model changed and I needed to update an entity. This involved changing an attribute from String? to [String]?. In order to make the migration I added a new version of the model. When I tried to set the current active model in the xcdatamodeld file, the file inspector was blank and there wasn’t a way to do it through the UI (Xcode 14.3.1). So, I tried opening the xcdatamoded file in Finder as a text file and modifying the _XCCurrentVersionName key in the XML, but that didn’t work either. The green checkmark still stayed on the old model. I ran git diff in my terminal and saw that the pbxproj file was modified. After some digging around I saw a XCVersionGroup in the pbxproj file, which looked like this:

/* Begin XCVersionGroup section */
        724C37322ABD9D030026634A /* Model.xcdatamodeld */ = {
            isa = XCVersionGroup;
            children = (
                724C37332ABD9D030026634A /* Model.xcdatamodel */,
                724C37342ABD9D030026634A /* Model 2.xcdatamodel */,
            );
            currentVersion = 724C37332ABD9D030026634A /* Model.xcdatamodel */;
            path = Cocoon.xcdatamodeld;
            sourceTree = "<group>";
            versionGroupType = wrapper.xcdatamodel;
        };
/* End XCVersionGroup section */

I updated the currentVersion to point to the Model 2 identifier. So it looked like this after the change:

/* Begin XCVersionGroup section */
        724C37322ABD9D030026634A /* Model.xcdatamodeld */ = {
            isa = XCVersionGroup;
            children = (
                724C37332ABD9D030026634A /* Model.xcdatamodel */,
                724C37342ABD9D030026634A /* Model 2.xcdatamodel */,
            );
            currentVersion = 724C37342ABD9D030026634A /* Model 2.xcdatamodel <-- THIS CHANGED> */;
            path = Cocoon.xcdatamodeld;
            sourceTree = "<group>";
            versionGroupType = wrapper.xcdatamodel;
        };
/* End XCVersionGroup section */

I restared Xcode and the Model 2 was selected as the active model version!