Difference among NSManagedObject(context:) constructor and NSEntityDescription.insertNewObject for inserting new object into CoreData

Question

The 2 code samples, able to insert new object into CoreData.

I was wondering, is there any difference among NSManagedObject(context:) and NSEntityDescription.insertNewObject, when comes to inserting new object?

When we should choose one over another?

NSManagedObject(context:)

let coreDataStack = CoreDataStack.INSTANCE
let backgroundContext = coreDataStack.backgroundContext

backgroundContext.perform {
    let nsTabInfo = NSTabInfo(context: backgroundContext)
    
    nsTabInfo.name = "..."
    
    if backgroundContext.hasChanges {
        do {
            try backgroundContext.save()
        } catch {
            let nserror = error as NSError
            fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
        }
    }
}

---

NSEntityDescription.insertNewObject

let coreDataStack = CoreDataStack.INSTANCE
let backgroundContext = coreDataStack.backgroundContext

backgroundContext.perform {
    let nsTabInfo = NSEntityDescription.insertNewObject(forEntityName: "NSTabInfo", into: backgroundContext) as! NSTabInfo
    
    nsTabInfo.name = "..."
    
    if backgroundContext.hasChanges {
        do {
            try backgroundContext.save()
        } catch {
            let nserror = error as NSError
            fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
        }
    }
}

Answer 1

Here's what the docs say for each of them.

---

convenience init(context moc: NSManagedObjectContext)

Initializes a managed object subclass and inserts it into the specified managed object context.

This method is only legal to call on subclasses of NSManagedObject that represent a single entity in the model.

---

class func insertNewObject(forEntityName entityName: String, 
                      into context: NSManagedObjectContext) -> NSManagedObject

Creates, configures, and returns an instance of the class for the entity with a given name.

This method makes it easy for you to create instances of a given entity without worrying about the details of managed object creation. The method is conceptually similar to the following code example.

---

The first one was introduced in iOS 10 and makes it more natural how the instantiation of the NSManagedObject should look like.

There are following differences in the two -

1. The second method forces you to use String for entityName - so it is error prone, while the first method always works with your NSManagedObject subclass without having to use Stringy name.
2. The first one is more readable than the second one.
3. There's a limitation of the first one - This method is only legal to call on subclasses of NSManagedObject that represent a single entity in the model., this may create issues in case you are using Entity subclassing within your data model like Animal > Dog. This line in the documentation refers to data models where more than one entity use the same class name. That's unusual but legal. Entity inheritance does not affect this.