It doesn't work well when all objects you want to add are new and haven't been inserted before. Try to first insert the Item object before adding the SubItem objects. For example let item = Item(name: "Item1", subitems: []) container.mainContext.insert(item) item.subitems.append(SubItem(name: "subItemA")) item.subitems.append(SubItem(name: "subItemB"))

Not cities.country.name but if you have a single city obj selected then city.country.name will work

You have a unique requirement on the attribute pair so there is only one Account object that has a given combination of the two attribute. Doesn’t that mean that you can skip the tuple and instead use the id property in your code? That is still use map and the same predicate but with id (or persistentModelId) instead of the tuple?

You have a single Category object that you update inside the loop instead of creating a new category for each iteration. Remove the category property and change your loop to something like this for index in 0..<model.dataTable!.rows.count { let row = model.dataTable!.rows[index] let name = row["Catagory"] as! String let category = Category(id: UUID(), name: name, instrumen: [[) context.insert(catagory) print(catagory.name) }

You are calling the wrong method, instead do modelContext.delete(model: MyModel.self)

You could create a constant variable and pass that let container = self.modelContext.container someFunc(container: container)