Adding Module Name to Core Data Entities

Question

I'm having trouble working out the implications of this note from Apple's "Using Swift with Cocoa and Objective-C":

Swift classes are namespaced—they’re scoped to the module (typically, the project) they are compiled in. To use a Swift subclass of the NSManagedObject class with your Core Data model, prefix the class name in the Class field in the model entity inspector with the name of your module.

I've done that, using my own application and just the stock master-detail template, so my entity's name is "Event" and its class is "Stock_Master_Detail.Event". When I then choose Create NSManagedObject Subclass from the Editor menu, and ask it to create a Swift subclass, it doesn't name the class right. Xcode creates a file called "Stock_Master_Detail.swift" with that's for a class called Stock_Master_Detail. And if I create multiple entities, all with the module name prefixed, Xcode can't generate more than one subclass since they'll all wind up having the same name.

I'll add that everything works fine in my limited testing if I just omit the module name entirely, counter to Apple's documentation. My question, then, is, what are the implications of not adding the module name to my class?

I have the same problem. My app's name contains spaces and I have tried every possible combination for the module name (using spaces, underscores, ...) to no avail. Without module name everything works fine. — zisoft

maschall maschall · Accepted Answer · 2015-01-15T18:45:08

One way I got around this is to leave the data model file alone, so in this case the class would be "Event". Then in the code where the NSManagedObjectModel is created (AppDelegate if you used Apple's project template) I changed it to:

lazy var managedObjectModel: NSManagedObjectModel = {
    // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
    let modelURL = NSBundle(forClass: self.classForCoder).URLForResource("Model", withExtension: "momd")!
    var bundleModel = NSManagedObjectModel(contentsOfURL: modelURL)!

    var objectModel = NSManagedObjectModel()
    objectModel.entities = bundleModel.entities.map { ( entity ) -> NSEntityDescription in
        var entityCopy = entity.copy() as NSEntityDescription
        entityCopy.managedObjectClassName = "Stock_Master_Detail." + entity.managedObjectClassName
        return entityCopy
    }

    return objectModel
    }()

One improvement, I would like to figure out is how to find the module name dynamically. I know I could parse the current class's name, but that feels a weirder than I want.

Adding Module Name to Core Data Entities

2 Answers