LinkingObjects
public final class LinkingObjects<T: Object>: LinkingObjectsBase
LinkingObjects is an auto-updating container type. It represents a collection of objects that
link to its parent object.
LinkingObjects can be queried with the same predicates as List<T> and Results<T>.
LinkingObjects always reflects the current state of the Realm on the current thread,
including during write transactions on the current thread. The one exception to
this is when using for...in enumeration, which will always enumerate over the
linking objects that were present when the enumeration is begun, even if some of them
are deleted or modified to no longer link to the target object during the enumeration.
LinkingObjects can only be used as a property on Object models. Properties of this type must
be declared as let and cannot be dynamic.
-
Returns the object at the given
index.Declaration
Swift
public subscript(index: Int) -> TParameters
indexThe index.
Return Value
The object at the given
index. -
The element type contained in this collection.
Declaration
Swift
public typealias Element = T -
The Realm which manages this linking objects collection, or
nilif the collection is unmanaged.Declaration
Swift
public var realm: Realm? -
Indicates if the linking objects collection is no longer valid.
The linking objects collection becomes invalid if
invalidateis called on the containingrealm.An invalidated linking objects can be accessed, but will always be empty.
Declaration
Swift
public var invalidated: Bool -
The number of objects in the linking objects.
Declaration
Swift
public var count: Int
-
Creates an instance of a
LinkingObjects. This initializer should only be called when declaring a property on a Realm model.Declaration
Swift
public init(fromType type: T.Type, property propertyName: String)Parameters
typeThe type of the object owning the property this
LinkingObjectsshould refer to.propertyNameThe property name of the property this
LinkingObjectsshould refer to. -
Returns a description of the objects contained within the linking objects.
Declaration
Swift
public override var description: String
-
Returns the index of an object in the linking objects collection, or
nilif the object is not present.Declaration
Swift
public func indexOf(object: T) -> Int?Parameters
objectThe object whose index is being queried.
-
Returns the index of the first object matching the given predicate, or
nilif no objects match.Declaration
Swift
public func indexOf(predicate: NSPredicate) -> Int?Parameters
predicateThe predicate with which to filter the objects.
-
Returns the index of the first object matching the given predicate, or
nilif no objects match.Declaration
Swift
public func indexOf(predicateFormat: String, _ args: AnyObject...) -> Int?Parameters
predicateFormatA predicate format string, optionally followed by a variable number of arguments.
-
Returns the first object in the linking objects collection, or
nilif the collection is empty.Declaration
Swift
public var first: T? -
Returns the last object in the linking objects collection, or
nilif collection is empty.Declaration
Swift
public var last: T?
-
Returns an
Arraycontaining the results of invokingvalueForKey(_:)withkeyon each of the linking objects collection’s objects.Declaration
Swift
public override func valueForKey(key: String) -> AnyObject?Parameters
keyThe name of the property whose values are desired.
-
Returns an
Arraycontaining the results of invokingvalueForKeyPath(_:)withkeyPathon each of the linking objects collection’s objects.Declaration
Swift
public override func valueForKeyPath(keyPath: String) -> AnyObject?Parameters
keyPathThe key path to the property whose values are desired.
-
Invokes
setValue(_:forKey:)on each of the linking objects collection’s objects using the specifiedvalueandkey.Warning
This method may only be called during a write transaction.
Declaration
Swift
public override func setValue(value: AnyObject?, forKey key: String)Parameters
valueThe value to set the property to.
keyThe name of the property whose value should be set on each object.
-
Returns a
Resultscontaining all objects matching the given predicate in the linking objects collection.Declaration
Swift
public func filter(predicateFormat: String, _ args: AnyObject...) -> Results<T>Parameters
predicateFormatA predicate format string, optionally followed by a variable number of arguments.
-
Returns a
Resultscontaining the objects in the linking objects collection, but sorted.Objects are sorted based on the values of the given property. For example, to sort a collection of
Students from youngest to oldest based on theirageproperty, you might callstudents.sorted("age", ascending: true).Warning
Collections may only be sorted by properties of boolean,
NSDate, single and double-precision floating point, integer, and string types.Declaration
Swift
public func sorted(property: String, ascending: Bool = true) -> Results<T>Parameters
propertyThe name of the property to sort by.
ascendingThe direction to sort in.
-
Returns a
Resultscontaining the objects in the linking objects collection, but sorted.Warning
Collections may only be sorted by properties of boolean,
NSDate, single and double-precision floating point, integer, and string types.Declaration
Swift
public func sorted<S: SequenceType where S.Generator.Element == SortDescriptor>(sortDescriptors: S) -> Results<T>Parameters
sortDescriptorsA sequence of
SortDescriptors to sort by.
-
Returns the minimum (lowest) value of the given property among all the objects represented by the linking objects collection.
Warning
Only a property whose type conforms to the
MinMaxTypeprotocol can be specified.Declaration
Swift
public func min<U: MinMaxType>(property: String) -> U?Parameters
propertyThe name of a property whose minimum value is desired.
Return Value
The minimum value of the property, or
nilif the collection is empty. -
Returns the maximum (highest) value of the given property among all the objects represented by the linking objects collection.
Warning
Only a property whose type conforms to the
MinMaxTypeprotocol can be specified.Declaration
Swift
public func max<U: MinMaxType>(property: String) -> U?Parameters
propertyThe name of a property whose minimum value is desired.
Return Value
The maximum value of the property, or
nilif the collection is empty. -
Returns the sum of the values of a given property over all the objects represented by the linking objects collection.
Warning
Only a property whose type conforms to the
AddableTypeprotocol can be specified.Declaration
Swift
public func sum<U: AddableType>(property: String) -> UParameters
propertyThe name of a property whose values should be summed.
Return Value
The sum of the given property.
-
Returns the average value of a given property over all the objects represented by the linking objects collection.
Warning
Only the name of a property whose type conforms to the
AddableTypeprotocol can be specified.Declaration
Swift
public func average<U: AddableType>(property: String) -> U?Parameters
propertyThe name of a property whose average value should be calculated.
Return Value
The average value of the given property, or
nilif the collection is empty.
-
Registers a block to be called each time the linking objects collection changes.
The block will be asynchronously called with the initial linking objects collection, and then called again after each write transaction which changes either any of the objects in the collection, or which objects are in the collection.
The
changeparameter that is passed to the block reports, in the form of indices within the collection, which of the objects were added, removed, or modified during each write transaction. See theRealmCollectionChangedocumentation for more information on the change information supplied and an example of how to use it to update aUITableView.At the time when the block is called, the linking objects collection will be fully evaluated and up-to-date, and as long as you do not perform a write transaction on the same thread or explicitly call
realm.refresh(), accessing it will never perform blocking work.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. This can include the notification with the initial set of objects. For example, the following code performs a write transaction immediately after adding the notification block, so there is no opportunity for the initial notification to be delivered first. As a result, the initial notification will reflect the state of the Realm after the write transaction.
let dog = realm.objects(Dog.self).first! let owners = dog.owners print("owners.count: \(owners.count)") // => 0 let token = owners.addNotificationBlock { changes in switch changes { case .Initial(let owners): // Will print "owners.count: 1" print("owners.count: \(owners.count)") break case .Update: // Will not be hit in this example break case .Error: break } } try! realm.write { realm.add(Person.self, value: ["name": "Mark", dogs: [dog]]) } // end of runloop execution contextYou must retain the returned token for as long as you want updates to be sent to the block. To stop receiving updates, call
stop()on the token.Warning
This method cannot be called during a write transaction, or when the containing Realm is read-only.
Declaration
Swift
public func addNotificationBlock(block: (RealmCollectionChange<LinkingObjects> -> Void)) -> NotificationTokenParameters
blockThe block to be called whenever a change occurs.
Return Value
A token which must be retained for as long as you want updates to be delivered.
-
Returns an
RLMGeneratorthat yields successive elements in the results.Declaration
Swift
public func generate() -> RLMGenerator<T>
-
The position of the first element in a non-empty collection. Identical to
endIndexin an empty collection.Declaration
Swift
public var startIndex: Int -
The collection’s
past the end
position.endIndexis not a valid argument to subscript, and is always reachable fromstartIndexby zero or more applications ofsuccessor().Declaration
Swift
public var endIndex: Int
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LinkingObjects Class Reference