RealmCollectionType
public protocol RealmCollectionType: CollectionType, CustomStringConvertible
A homogenous collection of Object
s which can be retrieved, filtered, sorted,
and operated upon.
-
The type of the objects contained in the collection.
Declaration
Swift
associatedtype Element: Object
-
The Realm which manages the collection, or
nil
for unmanaged collections.Declaration
Swift
var realm: Realm? { get }
-
Indicates if the collection can no longer be accessed.
The collection can no longer be accessed if
invalidate
is called on theRealm
that manages the collection.Declaration
Swift
var invalidated: Bool { get }
-
The number of objects in the collection.
Declaration
Swift
var count: Int { get }
-
A human-readable description of the objects contained in the collection.
Declaration
Swift
var description: String { get }
-
Returns the index of an object in the collection.
Declaration
Swift
func indexOf(object: Element) -> Int?
Parameters
object
An object.
Return Value
The index of the given object, or
nil
if the object is not in the collection. -
Returns the index of the first object matching the predicate.
Declaration
Swift
func indexOf(predicate: NSPredicate) -> Int?
Parameters
predicate
The predicate to use to filter the objects.
Return Value
The index of the first object that matches, or
nil
if no objects match. -
Returns the index of the first object matching the predicate.
Declaration
Swift
func indexOf(predicateFormat: String, _ args: AnyObject...) -> Int?
Parameters
predicateFormat
A predicate format string, optionally followed by a variable number of arguments.
Return Value
The index of the first object that matches, or
nil
if no objects match.
-
Returns all objects matching the given predicate in the collection.
Declaration
Swift
func filter(predicateFormat: String, _ args: AnyObject...) -> Results<Element>
Parameters
predicateFormat
A predicate format string, optionally followed by a variable number of arguments.
Return Value
A
Results
containing objects that match the given predicate. -
Returns all objects matching the given predicate in the collection.
Declaration
Swift
func filter(predicate: NSPredicate) -> Results<Element>
Parameters
predicate
The predicate to use to filter the objects.
Return Value
A
Results
containing objects that match the given predicate.
-
Returns a sorted
Results
from the collection.Declaration
Swift
func sorted<S: SequenceType where S.Generator.Element == SortDescriptor>(sortDescriptors: S) -> Results<Element>
Parameters
sortDescriptors
A sequence of
SortDescriptor
s to sort by.Return Value
A
Results
sorted by the specified properties.
-
Returns the minimum (lowest) value of the given property among all the objects represented by the collection.
Warning
Only a property whose type conforms to the
MinMaxType
protocol can be specified.Declaration
Swift
func min<U: MinMaxType>(property: String) -> U?
Parameters
property
The name of a property whose minimum value is desired.
Return Value
The minimum value of the property, or
nil
if the collection is empty. -
Returns the maximum (highest) value of the given property among all the objects represented by the collection.
Warning
Only a property whose type conforms to the
MinMaxType
protocol can be specified.Declaration
Swift
func max<U: MinMaxType>(property: String) -> U?
Parameters
property
The name of a property whose minimum value is desired.
Return Value
The maximum value of the property, or
nil
if the collection is empty. -
Returns the sum of the values of a given property over all the objects represented by the collection.
Warning
Only a property whose type conforms to the
AddableType
protocol can be specified.Declaration
Swift
func sum<U: AddableType>(property: String) -> U
Parameters
property
The 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 collection.
Warning
Only the name of a property whose type conforms to the
AddableType
protocol can be specified.Declaration
Swift
func average<U: AddableType>(property: String) -> U?
Parameters
property
The name of a property whose average value should be calculated.
Return Value
The average value of the given property, or
nil
if the collection is empty.
-
Returns an
Array
containing the results of invokingvalueForKey(_:)
withkey
on each of the collection’s objects.Declaration
Swift
func valueForKey(key: String) -> AnyObject?
Parameters
key
The name of the property.
Return Value
An
Array
containing the results. -
Returns an
Array
containing the results of invokingvalueForKeyPath(_:)
withkeyPath
on each of the collection’s objects.Declaration
Swift
func valueForKeyPath(keyPath: String) -> AnyObject?
Parameters
keyPath
The key path to the property.
Return Value
An
Array
containing the results. -
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
func setValue(value: AnyObject?, forKey key: String)
Parameters
value
The object value.
key
The name of the property.
-
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) print("dogs.count: \(dogs?.count)") // => 0 let token = dogs.addNotificationBlock { (changes: RealmCollectionChange) 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 continue 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
func addNotificationBlock(block: (RealmCollectionChange<Self>) -> Void) -> NotificationToken
Parameters
block
The 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.