CoreDataStack

public final class CoreDataStack
extension CoreDataStack: Equatable
extension CoreDataStack: CustomStringConvertible

An instance of CoreDataStack encapsulates the entire Core Data stack. It manages the managed object model, the persistent store coordinator, and managed object contexts.

It is composed of a main context and a background context. These two contexts operate on the main queue and a private background queue, respectively. Both are connected to the persistent store coordinator and data between them is perpetually kept in sync.

Changes to a child context are propagated to its parent context and eventually the persistent store when saving.

Warning

You cannot create a CoreDataStack instance directly. Instead, use a CoreDataStackProvider for initialization.

Typealiases

  • Describes the result type for creating a CoreDataStack.

    Declaration

    Swift

    public typealias StackResult = Result<CoreDataStack, Error>

Properties

  • The model for the stack.

    Declaration

    Swift

    public let model: CoreDataModel

  • The main managed object context for the stack, which operates on the main queue. This context is a root level context that is connected to the storeCoordinator. It is kept in sync with backgroundContext.

    Declaration

    Swift

    public let mainContext: NSManagedObjectContext

  • The background managed object context for the stack, which operates on a background queue. This context is a root level context that is connected to the storeCoordinator. It is kept in sync with mainContext.

    Declaration

    Swift

    public let backgroundContext: NSManagedObjectContext

  • The persistent store coordinator for the stack. Both contexts are connected to this coordinator.

    Declaration

    Swift

    public let storeCoordinator: NSPersistentStoreCoordinator

Child contexts

  • Creates a new child context with the specified concurrencyType and mergePolicyType.

    The parent context is either mainContext or backgroundContext dependending on the specified concurrencyType:

    Saving the returned context will propagate changes through the parent context and then to the persistent store.

    Declaration

    Swift

    public func childContext(concurrencyType: NSManagedObjectContextConcurrencyType = .mainQueueConcurrencyType,
                         mergePolicyType: NSMergePolicyType = .mergeByPropertyObjectTrumpMergePolicyType) -> NSManagedObjectContext.ChildContext

    Parameters

    concurrencyType

    The concurrency pattern to use. The default is .MainQueueConcurrencyType.
    mergePolicyType

    The merge policy to use. The default is .MergeByPropertyObjectTrumpMergePolicyType.

    Return Value

    A new child managed object context.

  • Resets the managed object contexts in the stack on their respective threads. Then, if the coordinator is connected to a persistent store, the store will be deleted and recreated on a background thread. The completion closure is executed on the main thread.

    Note

    Removing and re-adding the persistent store is performed on a background queue. For binary and SQLite stores, this will also remove the store from disk.

    Declaration

    Swift

    public func reset(onQueue queue: DispatchQueue = .global(qos: .userInitiated),
                  completion: @escaping (StackResult) -> Void)

    Parameters

    queue

    A background queue on which to reset the stack. The default is a background queue with a “user initiated” quality of service class.
    completion

    The closure to be called once resetting is complete. This is called on the main queue.