AnyRealmCollection

public struct AnyRealmCollection<Element> : RealmCollection, UntypedCollection where Element : RealmCollectionValue
extension AnyRealmCollection: RealmSubscribable

A type-erased RealmCollection.

Instances of RealmCollection forward operations to an opaque underlying collection having the same Element type.

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Properties

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

    Declaration

    Swift

    public var realm: Realm? { get }
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  • Indicates if the collection can no longer be accessed.

    The collection can no longer be accessed if invalidate() is called on the containing realm.

    Declaration

    Swift

    public var isInvalidated: Bool { get }
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  • The number of objects in the collection.

    Declaration

    Swift

    public var count: Int { get }
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  • A human-readable description of the objects contained in the collection.

    Declaration

    Swift

    public var description: String { get }
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Index Retrieval

  • Returns the index of the given object, or nil if the object is not in the collection.

    Declaration

    Swift

    public func index(of object: Element) -> Int?

    Parameters

    object

    An object.
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  • Returns the index of the first object matching the given predicate, or nil if no objects match.

    Declaration

    Swift

    public func index(matching predicate: NSPredicate) -> Int?

    Parameters

    predicate

    The predicate with which to filter the objects.
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Filtering

  • Returns a Results containing all objects matching the given predicate in the collection.

    Declaration

    Swift

    public func filter(_ predicate: NSPredicate) -> Results<Element>

    Parameters

    predicate

    The predicate with which to filter the objects.

    Return Value

    A Results containing objects that match the given predicate.

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Sorting

  • Returns a Results containing the objects in the collection, 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 their age property, you might call students.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) -> Results<Element>

    Parameters

    keyPath

    The key path to sort by.
    ascending

    The direction to sort in.
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  • Returns a Results containing the objects in the collection, but sorted.

    Warning

    Collections may only be sorted by properties of boolean, Date, NSDate, single and double-precision floating point, integer, and string types.

    See

    sorted(byKeyPath:ascending:)

    Declaration

    Swift

    public func sorted<S: Sequence>(by sortDescriptors: S) -> Results<Element>
    where S.Iterator.Element == SortDescriptor

    Parameters

    sortDescriptors

    A sequence of SortDescriptors to sort by.
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Aggregate Operations

  • Returns the minimum (lowest) value of the given property among all the objects in the collection, or nil if the collection is empty.

    Warning

    Only a property whose type conforms to the MinMaxType protocol can be specified.

    Declaration

    Swift

    public func min<T>(ofProperty property: String) -> T? where T : MinMaxType

    Parameters

    property

    The 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 objects in the collection, or nil if the collection is empty.

    Warning

    Only a property whose type conforms to the MinMaxType protocol can be specified.

    Declaration

    Swift

    public func max<T>(ofProperty property: String) -> T? where T : MinMaxType

    Parameters

    property

    The 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 objects in the collection.

    Warning

    Only a property whose type conforms to the AddableType protocol can be specified.

    Declaration

    Swift

    public func sum<T>(ofProperty property: String) -> T where T : AddableType

    Parameters

    property

    The name of a property whose values should be summed.
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  • Returns the average value of a given property over all the objects in the collection, or nil if the collection is empty.

    Warning

    Only the name of a property whose type conforms to the AddableType protocol can be specified.

    Declaration

    Swift

    public func average<T>(ofProperty property: String) -> T? where T : AddableType

    Parameters

    property

    The name of a property whose average value should be calculated.
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Sequence Support

Collection Support

  • 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 }
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  • 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 }
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Key-Value Coding

  • Returns an Array containing the results of invoking valueForKey(_:) with key on each of the collection’s objects.

    Declaration

    Swift

    public func value(forKey key: String) -> Any?

    Parameters

    key

    The name of the property whose values are desired.
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  • Returns an Array containing the results of invoking valueForKeyPath(_:) with keyPath on each of the collection’s objects.

    Declaration

    Swift

    public func value(forKeyPath keyPath: String) -> Any?

    Parameters

    keyPath

    The key path to the property whose values are desired.
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  • Invokes setValue(_:forKey:) on each of the collection’s objects using the specified value and key.

    Warning

    This method may only be called during a write transaction.

    Declaration

    Swift

    public func setValue(_ value: Any?, forKey key: String)

    Parameters

    value

    The value to set the property to.
    key

    The name of the property whose value should be set on each object.
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Notifications

  • 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 change parameter 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 the RealmCollectionChange documentation for more information on the change information supplied and an example of how to use it to update a UITableView.

    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 results = 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 context

    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.

    Warning

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

    Declaration

    Swift

    public func observe(on queue: DispatchQueue? = nil,
                    _ block: @escaping (RealmCollectionChange<AnyRealmCollection>) -> Void)
    -> NotificationToken

    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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Frozen Objects

  • Returns if this collection is frozen.

    Declaration

    Swift

    public var isFrozen: Bool { get }
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  • Returns a frozen (immutable) snapshot of this collection.

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

    Warning

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

    Warning

    Holding onto a frozen collection 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.

    Declaration

    Swift

    public func freeze() -> AnyRealmCollection
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  • Returns a live version of this frozen collection.

    This method resolves a reference to a live copy of the same frozen collection. If called on a live collection, will return itself.

    Declaration

    Swift

    public func thaw() -> AnyRealmCollection?
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