Core Data Coordinator for iOS 11 Apps

DataCoordinator.swift

final class DataCoordinator {
    //MARK: - singleton
    private static var coordinator: DataCoordinator?
    public class func sharedInstance() -> DataCoordinator {
        if coordinator == nil {
            coordinator = DataCoordinator()
        }
        return coordinator!
    }
    
    //MARK: - init
    public var container : NSPersistentContainer
    private init() {
        container = NSPersistentContainer(name: "Model")
        container.loadPersistentStores(completionHandler: { (_, error) in
            if let error = error {
                fatalError("Unresolved error \(error)")
            }
        })
    }
    
    //MARK: - perform methods
    static func performBackgroundTask(_ block: @escaping (NSManagedObjectContext) -> Void) {
        DataCoordinator.sharedInstance().container.performBackgroundTask(block)
    }
   
    static func performViewTask(_ block: @escaping (NSManagedObjectContext) -> Void) {
        block(DataCoordinator.sharedInstance().container.viewContext)
    }
}

read.swift

DataCoordinator.performViewTask { (context) in
    let eventFR : NSFetchRequest<DataEvent> = DataEvent.fetchRequest()
    do {
        eventFR.returnsObjectsAsFaults = false
        let res = try context.fetch(eventFR)
        print(res)
    } catch  {
        print("oops, could not fetch data in main thread")
    }
}

write.swift

DataCoordinator.performBackgroundTask { (context) in
    let obj = DataEvent(context: context)
    obj.title = "Test 6"
    do {
        print(context.hasChanges)
        try context.save()
        print("saved changes")
    } catch {
        print("exception saving in background thread")
    }
}