RLMEmbeddedObject

Objective-C

@interface RLMEmbeddedObject : RLMObjectBase <RLMThreadConfined>

Swift

class RLMEmbeddedObject : RLMObjectBase, RLMThreadConfined

RLMEmbeddedObject is a base class used to define Realm model objects.

Embedded objects work similarly to normal objects, but are owned by a single parent Object (which itself may be embedded). Unlike normal top-level objects, embedded objects cannot be directly created in or added to a Realm. Instead, they can only be created as part of a parent object, or by assigning an unmanaged object to a parent object’s property. Embedded objects are automatically deleted when the parent object is deleted or when the parent is modified to no longer point at the embedded object, either by reassigning an RLMObject property or by removing the embedded object from the array containing it.

Embedded objects can only ever have a single parent object which links to them, and attempting to link to an existing managed embedded object will throw an exception.

The property types supported on RLMEmbeddedObject are the same as for RLMObject, except for that embedded objects cannot link to top-level objects, so RLMObject and RLMArray<RLMObject> properties are not supported (RLMEmbeddedObject and RLMArray<RLMEmbeddedObject> are).

Embedded objects cannot have primary keys or indexed properties.

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Creating & Initializing Objects

  • Creates an unmanaged instance of a Realm object.

    Unmanaged embedded objects can be added to a Realm by assigning them to an object property of a managed Realm object or by adding them to a managed RLMArray.

    Declaration

    Objective-C

    - (nonnull instancetype)init;

    Swift

    init()
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  • Creates an unmanaged instance of a Realm object.

    Pass in an NSArray or NSDictionary instance to set the values of the object’s properties.

    Unmanaged embedded objects can be added to a Realm by assigning them to an object property of a managed Realm object or by adding them to a managed RLMArray.

    Declaration

    Objective-C

    - (nonnull instancetype)initWithValue:(nonnull id)value;

    Swift

    convenience init(value: Any)
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  • Returns the class name for a Realm object subclass.

    Warning

    Do not override. Realm relies on this method returning the exact class name.

    Declaration

    Objective-C

    + (nonnull NSString *)className;

    Swift

    class func className() -> String

    Return Value

    The class name for the model class.

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Properties

  • The Realm which manages the object, or nil if the object is unmanaged.

    Declaration

    Objective-C

    @property (nonatomic, readonly, nullable) RLMRealm *realm;

    Swift

    var realm: RLMRealm? { get }
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  • The object schema which lists the managed properties for the object.

    Declaration

    Objective-C

    @property (nonatomic, readonly) RLMObjectSchema *_Nonnull objectSchema;

    Swift

    var objectSchema: RLMObjectSchema { get }
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  • Indicates if the object can no longer be accessed because it is now invalid.

    An object can no longer be accessed if the object has been deleted from the Realm that manages it, or if invalidate is called on that Realm.

    Declaration

    Objective-C

    @property (nonatomic, readonly, getter=isInvalidated) BOOL invalidated;

    Swift

    var isInvalidated: Bool { get }
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  • Indicates if this object is frozen.

    See

    -[RLMEmbeddedObject freeze]

    Declaration

    Objective-C

    @property (nonatomic, readonly, getter=isFrozen) BOOL frozen;

    Swift

    var isFrozen: Bool { get }
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Customizing your Objects

  • Override this method to specify the default values to be used for each property.

    Declaration

    Objective-C

    + (nullable NSDictionary *)defaultPropertyValues;

    Swift

    class func defaultPropertyValues() -> [AnyHashable : Any]?

    Return Value

    A dictionary mapping property names to their default values.

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  • Override this method to specify the names of properties to ignore. These properties will not be managed by the Realm that manages the object.

    Declaration

    Objective-C

    + (nullable NSArray<NSString *> *)ignoredProperties;

    Swift

    class func ignoredProperties() -> [String]?

    Return Value

    An array of property names to ignore.

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  • Override this method to specify the names of properties that are non-optional (i.e. cannot be assigned a nil value).

    By default, all properties of a type whose values can be set to nil are considered optional properties. To require that an object in a Realm always store a non-nil value for a property, add the name of the property to the array returned from this method.

    Properties of RLMEmbeddedObject type cannot be non-optional. Array and NSNumber properties can be non-optional, but there is no reason to do so: arrays do not support storing nil, and if you want a non-optional number you should instead use the primitive type.

    Declaration

    Objective-C

    + (nonnull NSArray<NSString *> *)requiredProperties;

    Swift

    class func requiredProperties() -> [String]

    Return Value

    An array of property names that are required.

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  • Override this method to provide information related to properties containing linking objects.

    Each property of type RLMLinkingObjects must have a key in the dictionary returned by this method consisting of the property name. The corresponding value must be an instance of RLMPropertyDescriptor that describes the class and property that the property is linked to.

    return @{ @"owners": [RLMPropertyDescriptor descriptorWithClass:Owner.class propertyName:@"dogs"] };

    Declaration

    Objective-C

    + (nonnull NSDictionary<NSString *, RLMPropertyDescriptor *> *)
    linkingObjectsProperties;

    Swift

    class func linkingObjectsProperties() -> [String : RLMPropertyDescriptor]

    Return Value

    A dictionary mapping property names to RLMPropertyDescriptor instances.

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Notifications

  • Registers a block to be called each time the object changes.

    The block will be asynchronously called after each write transaction which deletes the object or modifies any of the managed properties of the object, including self-assignments that set a property to its existing value.

    For write transactions performed on different threads or in differen processes, the block will be called when the managing Realm is (auto)refreshed to a version including the changes, while for local write transactions it will be called at some point in the future after the write transaction is committed.

    Notifications are delivered via the standard run loop, and so can’t be delivered while the run loop is blocked by other activity. When notifications can’t be delivered instantly, multiple notifications may be coalesced into a single notification.

    Unlike with RLMArray and RLMResults, there is no “initial” callback made after you add a new notification block.

    Only objects which are managed by a Realm can be observed in this way. You must retain the returned token for as long as you want updates to be sent to the block. To stop receiving updates, call -invalidate on the token.

    It is safe to capture a strong reference to the observed object within the callback block. There is no retain cycle due to that the callback is retained by the returned token and not by the object itself.

    Warning

    This method cannot be called during a write transaction, when the containing Realm is read-only, or on an unmanaged object.

    Declaration

    Objective-C

    - (nonnull RLMNotificationToken *)addNotificationBlock:
    (nonnull RLMObjectChangeBlock)block;

    Swift

    func addNotificationBlock(_ block: @escaping RLMObjectChangeBlock) -> RLMNotificationToken

    Parameters

    block

    The block to be called whenever a change occurs.

    Return Value

    A token which must be held for as long as you want updates to be delivered.

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  • Registers a block to be called each time the object changes.

    The block will be asynchronously called after each write transaction which deletes the object or modifies any of the managed properties of the object, including self-assignments that set a property to its existing value.

    For write transactions performed on different threads or in different processes, the block will be called when the managing Realm is (auto)refreshed to a version including the changes, while for local write transactions it will be called at some point in the future after the write transaction is committed.

    Notifications are delivered on the given queue. If the queue is blocked and notifications can’t be delivered instantly, multiple notifications may be coalesced into a single notification.

    Unlike with RLMArray and RLMResults, there is no “initial” callback made after you add a new notification block.

    Only objects which are managed by a Realm can be observed in this way. You must retain the returned token for as long as you want updates to be sent to the block. To stop receiving updates, call -invalidate on the token.

    It is safe to capture a strong reference to the observed object within the callback block. There is no retain cycle due to that the callback is retained by the returned token and not by the object itself.

    Warning

    This method cannot be called during a write transaction, when the containing Realm is read-only, or on an unmanaged object.

    Warning

    The queue must be a serial queue.

    Declaration

    Objective-C

    - (nonnull RLMNotificationToken *)
    addNotificationBlock:(nonnull RLMObjectChangeBlock)block
                   queue:(nonnull dispatch_queue_t)queue;

    Swift

    func addNotificationBlock(_ block: @escaping RLMObjectChangeBlock, queue: DispatchQueue) -> RLMNotificationToken

    Parameters

    block

    The block to be called whenever a change occurs.
    queue

    The serial queue to deliver notifications to.

    Return Value

    A token which must be held for as long as you want updates to be delivered.

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Other Instance Methods

  • Returns YES if another Realm object instance points to the same object as the receiver in the Realm managing the receiver.

    For frozen objects and object types with a primary key, isEqual: is overridden to use the same logic as this method (along with a corresponding implementation for hash). Non-frozen objects without primary keys use pointer identity for isEqual: and hash.

    Declaration

    Objective-C

    - (BOOL)isEqualToObject:(nonnull RLMEmbeddedObject *)object;

    Swift

    func isEqual(to object: RLMEmbeddedObject) -> Bool

    Parameters

    object

    The object to compare the receiver to.

    Return Value

    Whether the object represents the same object as the receiver.

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  • Returns a frozen (immutable) snapshot of this object.

    The frozen copy is an immutable object which contains the same data as this object currently contains, but will not update when writes are made to the containing Realm. Unlike live objects, frozen objects can be accessed from any thread.

    Warning

    Holding onto a frozen object for an extended period while performing write transaction on the Realm may result in the Realm file growing to large sizes. See Realm.Configuration.maximumNumberOfActiveVersions for more information.

    Warning

    This method can only be called on a managed object.

    Declaration

    Objective-C

    - (nonnull instancetype)freeze;

    Swift

    func freeze() -> Self
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