AnyRealmCollection
public final class AnyRealmCollection<Element: RealmCollectionValue>: RealmCollection
A type-erased RealmCollection
.
Instances of RealmCollection
forward operations to an opaque underlying collection having the same Element
type.
-
The type of the objects contained within the collection.
Declaration
Swift
public typealias ElementType = Element
-
Declaration
Swift
public func index(after i: Int) -> Int
Parameters
i
-
Declaration
Swift
public func index(before i: Int) -> Int
Parameters
i
-
Creates an
AnyRealmCollection
wrappingbase
.Declaration
Swift
public init<C: RealmCollection>(_ base: C) where C.ElementType == Element
-
The Realm which manages the collection, or
nil
if the collection is unmanaged.Declaration
Swift
public var realm: Realm?
-
Indicates if the collection can no longer be accessed.
The collection can no longer be accessed if
invalidate()
is called on the containingrealm
.Declaration
Swift
public var isInvalidated: Bool
-
The number of objects in the collection.
Declaration
Swift
public var count: Int
-
A human-readable description of the objects contained in the collection.
Declaration
Swift
public var description: String
-
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.
-
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.
-
Returns the index of the first object matching the given predicate, or
nil
if no objects match.Declaration
Swift
public func index(matching predicateFormat: String, _ args: Any...) -> Int?
Parameters
predicateFormat
A predicate format string, optionally followed by a variable number of arguments.
-
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.
-
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
Student
s from youngest to oldest based on theirage
property, 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) -> Results<Element>
Parameters
keyPath
The key path to sort by.
ascending
The direction to sort in.
-
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.Declaration
Swift
public func sorted<S: Sequence>(by sortDescriptors: S) -> Results<Element> where S.Iterator.Element == SortDescriptor
Parameters
sortDescriptors
A sequence of
SortDescriptor
s to sort by.
-
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: MinMaxType>(ofProperty property: String) -> T?
Parameters
property
The name of a property whose minimum value is desired.
-
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: MinMaxType>(ofProperty property: String) -> T?
Parameters
property
The name of a property whose minimum value is desired.
-
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: AddableType>(ofProperty property: String) -> T
Parameters
property
The name of a property whose values should be summed.
-
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(ofProperty property: String) -> Double?
Parameters
property
The name of a property whose average value should be calculated.
-
Returns the object at the given
index
.Declaration
Swift
public subscript(position: Int) -> Element { return base[position] }
Parameters
index
The index.
-
Returns a
RLMIterator
that yields successive elements in the collection.Declaration
Swift
public func makeIterator() -> RLMIterator<Element>
-
The position of the first element in a non-empty collection. Identical to endIndex in an empty collection.
Declaration
Swift
public var startIndex: Int
-
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
-
Returns an
Array
containing the results of invokingvalueForKey(_:)
withkey
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.
-
Returns an
Array
containing the results of invokingvalueForKeyPath(_:)
withkeyPath
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.
-
Invokes
setValue(_:forKey:)
on each of the collection’s objects using the specifiedvalue
andkey
.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.
-
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 theRealmCollectionChange
documentation 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 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(_ 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.