List
public final class List<T: Object>: ListBase
List
is the container type in Realm used to define to-many relationships.
Like Swift’s Array
s, Lists are parameterized on a single Object
subclass (T
).
Lists can be filtered and sorted with the same predicates as Results<T>
.
When added as a property on Object
models, the property must be declared as let
and cannot be dynamic
.
-
The type of the elements contained within this list.
Declaration
Swift
public typealias Element = T
-
Returns the object at the given index (get), or replaces the object at the given index (set).
Warning
You can only set an object during a write transaction.
Declaration
Swift
public subscript(index: Int) -> T
Parameters
index
The index of the object to retrieve or replace.
Return Value
The object at the given
index
. -
The Realm which manages the list. Returns
nil
for unmanaged lists.Declaration
Swift
public var realm: Realm?
-
Indicates if the list can no longer be accessed.
Declaration
Swift
public var invalidated: Bool { return _rlmArray.invalidated }
-
Creates a
List
that holds objects of typeT
.Declaration
Swift
public override init()
-
Returns the index of an object in the list.
Declaration
Swift
public func indexOf(object: T) -> Int?
Parameters
object
An object to find.
Return Value
The index of the object, or
nil
if the object is not in the list. -
Returns the index of the first object in the list matching the predicate.
Declaration
Swift
public func indexOf(predicate: NSPredicate) -> Int?
Parameters
predicate
The predicate with which to filter the objects.
Return Value
The index of the first matching object, or
nil
if no objects match. -
Returns the index of the first object in the list matching the predicate.
Declaration
Swift
public 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 matching object, or
nil
if no objects match.
-
Returns the first object in the list, or
nil
if the list is empty.Declaration
Swift
public var first: T? { return _rlmArray.firstObject() as! T? }
-
Returns the last object in the list, or
nil
if the list is empty.Declaration
Swift
public var last: T? { return _rlmArray.lastObject() as! T? }
-
Returns an
Array
containing the results of invokingvalueForKey(_:)
usingkey
on each of the collection’s objects.Declaration
Swift
public override 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(_:)
usingkeyPath
on each of the collection’s objects.Declaration
Swift
public override 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 can only be called during a write transaction.
Declaration
Swift
public override func setValue(value: AnyObject?, forKey key: String)
Parameters
value
The object value.
key
The name of the property.
-
Returns all objects matching the given predicate in the list.
Declaration
Swift
public func filter(predicateFormat: String, _ args: AnyObject...) -> Results<T>
Parameters
predicateFormat
A predicate format string; variable arguments are supported.
Return Value
A
Results
containing objects that match the predicate. -
Returns all objects matching the given predicate in the list.
Declaration
Swift
public func filter(predicate: NSPredicate) -> Results<T>
Parameters
predicate
The predicate with which to filter the objects.
Return Value
A
Results
containing objects that match the predicate.
-
Returns a sorted
Results
from the list.Declaration
Swift
public func sorted(property: String, ascending: Bool = true) -> Results<T>
Parameters
property
The property name to sort by.
ascending
The direction to sort by.
Return Value
A
Results
containing the list objects sorted by the specified property. -
Returns a sorted
Results
from the list.Declaration
Swift
public func sorted<S: SequenceType where S.Generator.Element == SortDescriptor>(sortDescriptors: S) -> Results<T>
Parameters
sortDescriptors
An sequence of
SortDescriptor
s to sort by.Return Value
A
Results
containing the list objects sorted by the specified property.
-
Returns the minimum (lowest) value of the given property among all the objects in the list.
Warning
Only a property whose type conforms to the
MinMaxType
protocol can be specified.Declaration
Swift
public 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 list is empty. -
Returns the maximum (highest) value of the given property among all the objects in the list.
Warning
Only a property whose type conforms to the
MinMaxType
protocol can be specified.Declaration
Swift
public func max<U: MinMaxType>(property: String) -> U?
Parameters
property
The name of a property whose maximum value is desired.
Return Value
The maximum value of the property, or ’
nil
if the list is empty. -
Returns the sum of the values of a given property over all the objects in the list.
Warning
Only a property whose type conforms to the
AddableType
protocol can be specified.Declaration
Swift
public 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 in the list.
Warning
Only a property whose type conforms to the
AddableType
protocol can be specified.Declaration
Swift
public 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.
-
Appends the given object to the end of the list.
If the object is managed by a different Realm than the receiver, a copy is made and added to the Realm managing the receiver.
Warning
This method may only be called during a write transaction.
Declaration
Swift
public func append(object: T)
Parameters
object
An object.
-
Appends the objects in the given sequence to the end of the list.
Warning
This method may only be called during a write transaction.
Declaration
Swift
public func appendContentsOf<S: SequenceType where S.Generator.Element == T>(objects: S)
Parameters
objects
A sequence of objects.
-
Inserts an object at the given index.
Warning
This method may only be called during a write transaction.
Warning
This method will throw an exception if called with an invalid index.
Declaration
Swift
public func insert(object: T, atIndex index: Int)
Parameters
object
An object.
index
The index at which to insert the object.
-
Removes an object at the given index. The object is not removed from the Realm that manages it.
Warning
This method may only be called during a write transaction.
Warning
This method will throw an exception if called with an invalid index.
Declaration
Swift
public func removeAtIndex(index: Int)
Parameters
index
The index at which to remove the object.
-
Removes the last object in the list. The object is not removed from the Realm that manages it.
Warning
This method may only be called during a write transaction.Declaration
Swift
public func removeLast()
-
Removes all objects from the list. The objects are not removed from the Realm that manages them.
Warning
This method may only be called during a write transaction.Declaration
Swift
public func removeAll()
-
Replaces an object at the given index with a new object.
Warning
This method may only be called during a write transaction.
Warning
This method will throw an exception if called with an invalid index.
Declaration
Swift
public func replace(index: Int, object: T)
Parameters
index
The index of the object to be replaced.
object
An object.
-
Moves the object at the given source index to the given destination index.
Warning
This method may only be called during a write transaction.
Warning
This method will throw an exception if called with invalid indices.
Declaration
Swift
public func move(from from: Int, to: Int) { // swiftlint:disable:this variable_name
Parameters
from
The index of the object to be moved.
to
index to which the object at
from
should be moved. -
Exchanges the objects in the list at given indices.
Warning
This method may only be called during a write transaction.
Warning
This method will throw an exception if called with invalid indices.
Declaration
Swift
public func swap(index1: Int, _ index2: Int)
Parameters
index1
The index of the object which should replace the object at index
index2
.index2
The index of the object which should replace the object at index
index1
.
-
Registers a block to be called each time the list changes.
The block will be asynchronously called with the initial list, and then called again after each write transaction which changes the list or any of the items in the list.
The
change
parameter that is passed to the block reports, in the form of indices within the list, 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
.The block is called on the same thread as it was added on, and can only be added on threads which are currently within a run loop. Unless you are specifically creating and running a run loop on a background thread, this will normally only be the main thread.
Notifications can’t be delivered as long as 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 list. 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, and will not include change information.
let person = realm.objects(Person).first! print("dogs.count: \(person.dogs.count)") // => 0 let token = person.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.Warning
This method may only be called on a managed list.
Declaration
Swift
public func addNotificationBlock(block: (RealmCollectionChange<List>) -> ()) -> NotificationToken
Parameters
block
The block to be called each time the list changes.
Return Value
A token which must be held for as long as you want updates to be delivered.
-
Returns a
GeneratorOf<T>
that yields successive elements in the list.Declaration
Swift
public func generate() -> RLMGenerator<T>
-
Replace the given
subRange
of elements withnewElements
.Declaration
Swift
public func replaceRange<C: CollectionType where C.Generator.Element == T>(subRange: Range<Int>, with newElements: C)
Parameters
subRange
The range of elements to be replaced.
newElements
The new elements to be inserted into the list.
-
The position of the first element in a non-empty collection. Identical to
endIndex
in an empty collection.Declaration
Swift
public var startIndex: Int { return 0 }
-
The collection’s
past the end
position.endIndex
is not a valid argument to subscript, and is always reachable fromstartIndex
by zero or more applications ofsuccessor()
.Declaration
Swift
public var endIndex: Int { return count }