Inherits from NSOperation
Declared in RKRelationshipConnectionOperation.h

Overview

The RKRelationshipConnectionOperation class is a subclass of NSOperation that manages the connection of NSManagedObject relationships as described by an RKConnectionDescription object. When executed, the operation will find related objects by searching the associated managed object cache for objects matching the connection description and setting them as the value for the relationship being connected.

For example, given a managed object for the Employee entity with a one-to-one relationship to a Company named company (with an inverse relationship one-to-many relationship named employees) and a connection specifying that the relationship can be connected by finding the Company managed object whose companyID attribute matches the companyID of the Employee, the operation would find the Company that employs the Employee by primary key and set the Core Data relationship to reflect the relationship appropriately.

Tasks

Initializing a Relationship Connection Operation

Accessing Details About the Operation

  •   managedObject

    The managed object the receiver will attempt to connect a relationship for.

         property
  •   connections

    An array of RKConnectionDescription objects describing the relationship connection the receiver will attempt to connect.

         property
  •   managedObjectCache

    The managed object cache the receiver will use to fetch a related object satisfying the connection mapping.

         property
  •   connectedValuesByRelationshipName

    A dictionary keyed by the name of each relationship that was established by the receiver wherein each value is the objects or objects that were connected.

         property

Setting the Connection Block

Properties

connectedValuesByRelationshipName

A dictionary keyed by the name of each relationship that was established by the receiver wherein each value is the objects or objects that were connected.

@property (nonatomic, strong, readonly) NSDictionary *connectedValuesByRelationshipName

Discussion

For each key in the dictionary, the value will either be [NSNull null], indicating that the relationship could not be connected, a single NSManagedObject object (if the relationship is one-to-one), or an array of NSManagedObject objects (if the relationship is one-to-many).

Declared In

RKRelationshipConnectionOperation.h

connections

An array of RKConnectionDescription objects describing the relationship connection the receiver will attempt to connect.

@property (nonatomic, strong, readonly) NSArray *connections

Declared In

RKRelationshipConnectionOperation.h

managedObject

The managed object the receiver will attempt to connect a relationship for.

@property (nonatomic, strong, readonly) NSManagedObject *managedObject

Declared In

RKRelationshipConnectionOperation.h

managedObjectCache

The managed object cache the receiver will use to fetch a related object satisfying the connection mapping.

@property (nonatomic, strong, readonly) id<RKManagedObjectCaching> managedObjectCache

Declared In

RKRelationshipConnectionOperation.h

Instance Methods

initWithManagedObject:connections:managedObjectCache:

Initializes the receiver with a given managed object, connection mapping, and managed object cache.

- (id)initWithManagedObject:(NSManagedObject *)managedObject connections:(NSArray *)connections managedObjectCache:(id<RKManagedObjectCaching>)managedObjectCache

Parameters

managedObject

The object to attempt to connect a relationship to.

connections

An array of connection objects describing how establish a Core Data relationship between objects.

managedObjectCache

The managed object cache from which to attempt to fetch a matching object to satisfy the connection.

Return Value

The receiver, initialized with the given managed object, connection mapping, and managed object cache.

Declared In

RKRelationshipConnectionOperation.h

setConnectionBlock:

Sets a block to be executed on the operation attempted to establish the connection.

- (void)setConnectionBlock:(void ( ^ ) ( RKRelationshipConnectionOperation *operation , RKConnectionDescription *connection , id connectedValue ))block

Parameters

block

A block object to be executed when the connection is evaluated. The block accepts two arguments: the operation itself and the value, if any, that was set for the relationship targetted by the connection description.

Discussion

Unlike the block set with setCompletionBlock:, this block is executed during the body of the operation within the queue of the managed object context in which the connection was established. This means that it is safe to executed both the connectedValue and managedObject directly within the body of the block.

Declared In

RKRelationshipConnectionOperation.h