Core Data in iOS 10

Core Data has been highly improved and can be considered generally good in iOS 10.

Core Data stack.

I believe many developers experienced really bad pain in the beginning when setting up Core Data stack.
Core Data stack is about how to setting up NSManagedObjectModel, NSPersistentStoreCoordinator, NSManagedObjectContext, since these components only does partial functionality, you have to set up Core Data stack according to your application's design. This means there's no such a best practice.

(Bit Nerd Ranch mentioned some common stacks: Introducing the Open-Source Big Nerd Ranch Core Data Stack)

Flexibility is good, developer friendly is important.

We got NSPersistentContainer in iOS 10.
The main purpose of NSPersistentContainer is to simplify the process of setting up Core Data stacks and provide some useful utils for our daily usage.

let container = NSPersistentContainer(name: "DataModel")  
container.loadPersistentStores(completionHandler: { [weak self](storeDescription, error) in  
    if let error = error {
        NSLog("CoreData error \(error), \(error._userInfo)")
        self?.errorHandler(error)
    }
  }
)

If you ever developed with Core Data stacks you probably know this is a huge improvement.

container.viewContext.perform {  
  // foreground task
}

container.performBackgroundTask {  
  // background task
} 

NSPersistentContainer handles task as well, a really good utils.

NSPersistentContainer is nothing but a wrapper, providing some default values and behaviours. So we don't have to worry about futher configuration.

Xcode 8 codegen

Xcode 8 introduced NSManagedObject's codegen, we used to created NSManagedObject subclass by ourselves which is representing xcdatamodel's entity.

You don't have to do it anymore, when your xcdatamodel file is modified and saved, Xcode generates corresponding NSManagedObject subclass for you, automatically.

btw, Xcode's codegen is not as powerful as mogenerator, but good enough for beginner. (no commands no setups)

Finally, I can introduce Core Data as a persistence store option for my beginner friends.