Results
public struct Results<Element> : Equatable where Element : RealmCollectionValue
Results is an auto-updating container type in Realm returned from object queries.
Results can be queried with the same predicates as List<Element>, and you can
chain queries to further filter query results.
Results always reflect 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 objects which matched the query when the enumeration is begun, even if some of them are deleted or modified to be
excluded by the filter during the enumeration.
Results are lazily evaluated the first time they are accessed; they only run queries when the result of the query is
requested. This means that chaining several temporary Results to sort and filter your data does not perform any
unnecessary work processing the intermediate state.
Once the results have been evaluated or a notification block has been added, the results are eagerly kept up-to-date, with the work done to keep them up-to-date done on a background thread whenever possible.
Results instances cannot be directly instantiated.
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A human-readable description of the objects represented by the results.
Declaration
Swift
public var description: String { get } -
The type of the objects described by the results.
Declaration
Swift
public typealias ElementType = Element
-
The Realm which manages this results. Note that this property will never return
nil.Declaration
Swift
public var realm: Realm? { get } -
Indicates if the results are no longer valid.
The results becomes invalid if
invalidate()is called on the containingrealm. An invalidated results can be accessed, but will always be empty.Declaration
Swift
public var isInvalidated: Bool { get } -
The number of objects in the results.
Declaration
Swift
public var count: Int { get }
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Returns the index of the given object in the results, or
nilif the object is not present.Declaration
Swift
public func index(of object: Element) -> Int? -
Returns the index of the first object matching the predicate, or
nilif no objects match.Declaration
Swift
public func index(matching predicate: NSPredicate) -> Int?Parameters
predicateThe predicate with which to filter the objects.
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Returns the index of the first object matching the predicate, or
nilif no objects match.Declaration
Swift
public func index(matching predicateFormat: String, _ args: Any...) -> Int?Parameters
predicateFormatA predicate format string, optionally followed by a variable number of arguments.
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Returns the object at the given
index.Declaration
Swift
public subscript(position: Int) -> Element { get }Parameters
indexThe index.
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Returns the first object in the results, or
nilif the results are empty.Declaration
Swift
public var first: Element? { get } -
Returns the last object in the results, or
nilif the results are empty.Declaration
Swift
public var last: Element? { get }
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Returns an
Arraycontaining the results of invokingvalueForKey(_:)withkeyon each of the results.Declaration
Swift
public func value(forKey key: String) -> Any?Parameters
keyThe name of the property whose values are desired.
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Returns an
Arraycontaining the results of invokingvalueForKeyPath(_:)withkeyPathon each of the results.Declaration
Swift
public func value(forKeyPath keyPath: String) -> Any?Parameters
keyPathThe key path to the property whose values are desired.
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Invokes
setValue(_:forKey:)on each of the objects represented by the results using the specifiedvalueandkey.Warning
This method may only be called during a write transaction.
Declaration
Swift
public func setValue(_ value: Any?, forKey key: String)Parameters
valueThe object value.
keyThe name of the property whose value should be set on each object.
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Returns a
Resultscontaining all objects matching the given predicate in the collection.Declaration
Swift
public func filter(_ predicateFormat: String, _ args: Any...) -> Results<Element>Parameters
predicateFormatA predicate format string, optionally followed by a variable number of arguments.
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Returns a
Resultscontaining all objects matching the given predicate in the collection.Declaration
Swift
public func filter(_ predicate: NSPredicate) -> Results<Element>Parameters
predicateThe predicate with which to filter the objects.
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Returns a
Resultscontaining the objects represented by the results, but sorted.Objects are sorted based on the values of the given key path. For example, to sort a collection of
Students from youngest to oldest based on theirageproperty, you might callstudents.sorted(byKeyPath: "age", ascending: true).Warning
Collections may only be sorted by properties of boolean,
Date,NSDate, single and double-precision floating point, integer, and string types.Declaration
Swift
public func sorted(byKeyPath keyPath: String, ascending: Bool = true) -> Results<Element>Parameters
keyPathThe key path to sort by.
ascendingThe direction to sort in.
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Returns a
Resultscontaining the objects represented by the results, but sorted.Warning
Collections may only be sorted by properties of boolean,
Date,NSDate, single and double-precision floating point, integer, and string types.Declaration
Swift
public func sorted<S: Sequence>(by sortDescriptors: S) -> Results<Element> where S.Iterator.Element == SortDescriptorParameters
sortDescriptorsA sequence of
SortDescriptors to sort by. -
Returns a
Resultscontaining distinct objects based on the specified key pathsDeclaration
Swift
public func distinct<S: Sequence>(by keyPaths: S) -> Results<Element> where S.Iterator.Element == StringParameters
keyPathsThe key paths used produce distinct results
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Returns the minimum (lowest) value of the given property among all the results, or
nilif the results are empty.Warning
Only a property whose type conforms to the
MinMaxTypeprotocol can be specified.Declaration
Swift
public func min<T>(ofProperty property: String) -> T? where T : MinMaxTypeParameters
propertyThe name of a property whose minimum value is desired.
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Returns the maximum (highest) value of the given property among all the results, or
nilif the results are empty.Warning
Only a property whose type conforms to the
MinMaxTypeprotocol can be specified.Declaration
Swift
public func max<T>(ofProperty property: String) -> T? where T : MinMaxTypeParameters
propertyThe name of a property whose minimum value is desired.
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Returns the sum of the values of a given property over all the results.
Warning
Only a property whose type conforms to the
AddableTypeprotocol can be specified.Declaration
Swift
public func sum<T>(ofProperty property: String) -> T where T : AddableTypeParameters
propertyThe name of a property whose values should be summed.
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Returns the average value of a given property over all the results, or
nilif the results are empty.Warning
Only the name of a property whose type conforms to the
AddableTypeprotocol can be specified.Declaration
Swift
public func average<T>(ofProperty property: String) -> T? where T : AddableTypeParameters
propertyThe name of a property whose average value should be calculated.
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Registers a block to be called each time the collection changes.
The block will be asynchronously called with the initial results, 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 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 collection.
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 dogs = realm.objects(Dog.self) print("dogs.count: \(dogs?.count)") // => 0 let token = dogs.observe { changes in switch changes { case .initial(let dogs): // Will print "dogs.count: 1" print("dogs.count: \(dogs.count)") break case .update: // Will not be hit in this example break case .error: break } } try! realm.write { let dog = Dog() dog.name = "Rex" person.dogs.append(dog) } // end of run loop 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
invalidate()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 observe(_ block: @escaping (RealmCollectionChange<Results>) -> Void) -> NotificationTokenParameters
blockThe 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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Returns a
RLMIteratorthat yields successive elements in the results.Declaration
Swift
public func makeIterator() -> RLMIterator<Element>
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The position of the first element in a non-empty collection. Identical to endIndex in an empty collection.
Declaration
Swift
public var startIndex: Int { get } -
The collection’s
past the end
position. endIndex is not a valid argument to subscript, and is always reachable from startIndex by zero or more applications of successor().Declaration
Swift
public var endIndex: Int { get } -
Declaration
Swift
public func index(after i: Int) -> Int -
Declaration
Swift
public func index(before i: Int) -> Int
-
Declaration
Swift
public func encode(to encoder: Encoder) throws
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Subscribe to the query represented by this
ResultsSubscribing to a query asks the server to synchronize all objects to the client which match the query, along with all objects which are reachable from those objects via links. This happens asynchronously, and the local client Realm may not immediately have all objects which match the query. Observe the
stateproperty of the returned subscription object to be notified of when the subscription has been processed by the server and all objects matching the query are available.
Creating a new subscription with the same name and query as an existing subscription will not create a new subscription, but instead will return an object referring to the existing sync subscription. This means that performing the same subscription twice followed by removing it once will result in no subscription existing.
By default trying to create a subscription with a name as an existing subscription with a different query or options will fail. If
updateistrue, instead the existing subscription will be changed to use the query and options from the new subscription. This only works if the new subscription is for the same type of objects as the existing subscription, and trying to overwrite a subscription with a subscription of a different type of objects will still fail.
The number of top-level objects which are included in the subscription can optionally be limited by setting the
limitparamter. If more top-level objects than the limit match the query, only the firstlimitobjects will be included. This respects the sort and distinct order of the query being subscribed to for the determination of what thefirst
objects are.The limit does not count or apply to objects which are added indirectly due to being linked to by the objects in the subscription or due to being listed in
includeLinkingObjects. If the limit is larger than the number of objects which match the query, all objects will be included.
By default subscriptions are persistent, and last until they are explicitly removed by calling
unsubscribe(). Subscriptions can instead be made temporary by setting the time to live to how long the subscription should remain. After that time has elapsed the subscription will be automatically removed.
Outgoing links (i.e.
ListandObjectproperties) are automatically included in sync subscriptions. That is, if you subscribe to a query which matches one object, every object which is reachable via links from that object are also included in the subscription. By default,LinkingObjectsproperties do not work this way and instead, they only report objects which happen to be included in a subscription. SpecificLinkingObjectsproperties can be explicitly included in the subscription by naming them in theincludingLinkingObjectsarray. Any keypath which ends in aLinkingObjectsproperty can be included in this array, including ones involving intermediate links.
Creating a subscription is an asynchronous operation and the newly created subscription will not be reported by Realm.subscriptions() until it has transitioned from the
.creatingstate to.pending,.createdor.error.Declaration
Swift
public func subscribe(named subscriptionName: String? = nil, limit: Int? = nil, update: Bool = false, timeToLive: TimeInterval? = nil, includingLinkingObjects: [String] = []) -> SyncSubscriptionParameters
subscriptionNameAn optional name for the subscription.
limitThe maximum number of top-level objects to include in the subscription.
updateWhether an existing subscription with the same name should be updated or if it should be an error.
timeToLiveHow long in seconds this subscription should remain active.
includingLinkingObjectsWhich
LinkingObjectsproperties should pull in the contained objects.Return Value
The subscription.
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Results Structure Reference