more specific to my request: I have written two DBs: 1) Libre Office Base 2) MobiDB Does anyone have experience using any of these? Could you give me an example of an app in XCode to connect, read and write tables of at least one of them? Thank you

Thanks for the reply. I'm quite confused. I didn't create anything manually. I limited myself to defining the entities and then using the "Editor>Create NSManaged Subclass" function I tried to create the two files of ..Class and ...Properties. Xcode created the two files and inside it encoded the Class definition with the name of the entity but at this point underlining the name of the entity it gives the error message "invalid Redefinition.... If I delete the two files created by Xcode I no longer have the definition of the class to refer to to save the data anywhere.