List
public final class List<T: Object>: ListBase
List<T>
is the container type in Realm used to define to-many relationships.
Lists hold a single Object
subclass (T
) which defines the type
of the List.
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
.
-
Element type contained in this collection.
Declaration
Swift
public typealias Element = T
-
Returns the object at the given
index
on get. Replaces the object at the givenindex
on set.Warning
You can only set an object during a write transaction.
Declaration
Swift
public subscript(index: Int) -> T
Parameters
index
The index.
Return Value
The object at the given
index
. -
The Realm the objects in this List belong to, or
nil
if the List’s owning object does not belong to a Realm (the List is standalone).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 the given object, or
nil
if the object is not in the List.Declaration
Swift
public func indexOf(object: T) -> Int?
Parameters
object
The object whose index is being queried.
Return Value
The index of the given object, or
nil
if the object is not in the List. -
Returns the index of the first object matching the given predicate, or
nil
no objects match.Declaration
Swift
public func indexOf(predicate: NSPredicate) -> Int?
Parameters
predicate
The
NSPredicate
used 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 matching the given predicate, or
nil
if no objects match.Declaration
Swift
public func indexOf(predicateFormat: String, _ args: AnyObject...) -> Int?
Parameters
predicateFormat
The 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 empty.Declaration
Swift
public var first: T? { return _rlmArray.firstObject() as! T? }
-
Returns the last object in the List, or
nil
if empty.Declaration
Swift
public var last: T? { return _rlmArray.lastObject() as! T? }
-
Returns an Array containing the results of invoking
valueForKey(_:)
using key 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
Array containing the results of invoking
valueForKey(_:)
using key on each of the collection’s objects. -
Returns an Array containing the results of invoking
valueForKeyPath(_:)
using keyPath 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
Array containing the results of invoking
valueForKeyPath(_:)
using keyPath on each of the collection’s objects. -
Invokes
setValue(_:forKey:)
on each of the collection’s objects using the specified value and key.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
Results
containing elements that match the given predicate.Declaration
Swift
public func filter(predicateFormat: String, _ args: AnyObject...) -> Results<T>
Parameters
predicateFormat
The predicate format string which can accept variable arguments.
Return Value
Results
containing elements that match the given predicate.
-
Returns
Results
containing elements sorted by the given property.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
Results
containing elements sorted by the given property. -
Returns
Results
with elements sorted by the given sort descriptors.Declaration
Swift
public func sorted<S: SequenceType where S.Generator.Element == SortDescriptor>(sortDescriptors: S) -> Results<T>
Parameters
sortDescriptors
SortDescriptor
s to sort by.Return Value
Results
with elements sorted by the given sort descriptors.
-
Returns the minimum value of the given property.
Warning
Only names of properties of a type conforming to the
MinMaxType
protocol can be used.Declaration
Swift
public func min<U: MinMaxType>(property: String) -> U?
Parameters
property
The name of a property conforming to
MinMaxType
to look for a minimum on.Return Value
The minimum value for the property amongst objects in the List, or
nil
if the List is empty. -
Returns the maximum value of the given property.
Warning
Only names of properties of a type conforming to the
MinMaxType
protocol can be used.Declaration
Swift
public func max<U: MinMaxType>(property: String) -> U?
Parameters
property
The name of a property conforming to
MinMaxType
to look for a maximum on.Return Value
The maximum value for the property amongst objects in the List, or
nil
if the List is empty. -
Returns the sum of the given property for objects in the List.
Warning
Only names of properties of a type conforming to the
AddableType
protocol can be used.Declaration
Swift
public func sum<U: AddableType>(property: String) -> U
Parameters
property
The name of a property conforming to
AddableType
to calculate sum on.Return Value
The sum of the given property over all objects in the List.
-
Returns the average of the given property for objects in the List.
Warning
Only names of properties of a type conforming to the
AddableType
protocol can be used.Declaration
Swift
public func average<U: AddableType>(property: String) -> U?
Parameters
property
The name of a property conforming to
AddableType
to calculate average on.Return Value
The average of the given property over all objects in the List, or
nil
if the List is empty.
-
Appends the given object to the end of the List. If the object is from a different Realm it is copied to the List’s Realm.
Warning
This method can 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 can 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 the given object at the given index.
Warning
This method can only be called during a write transaction.Warning
Throws an exception when called with an index smaller than zero or greater than or equal to the number of objects in the List.
Declaration
Swift
public func insert(object: T, atIndex index: Int)
Parameters
object
An object.
index
The index at which to insert the object.
-
Removes the object at the given index from the List. Does not remove the object from the Realm.
Warning
This method can only be called during a write transaction.Warning
Throws an exception when called with an index smaller than zero or greater than or equal to the number of objects in the List.
Declaration
Swift
public func removeAtIndex(index: Int)
Parameters
index
The index at which to remove the object.
-
Removes the last object in the List. Does not remove the object from the Realm.
Warning
This method can only be called during a write transaction.Declaration
Swift
public func removeLast()
-
Removes all objects from the List. Does not remove the objects from the Realm.
Warning
This method can 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 can only be called during a write transaction.Warning
Throws an exception when called with an index smaller than zero or greater than or equal to the number of objects in the List.
Declaration
Swift
public func replace(index: Int, object: T)
Parameters
index
The index of the object to be replaced.
object
An object to replace at the specified index.
-
Moves the object at the given source index to the given destination index.
Warning
This method can only be called during a write transaction.Warning
Throws an exception when called with an index smaller than zero or greater than or equal to the number of objects in the List.
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 indexes.
Warning
Throws an exception when either index exceeds the bounds of the List.Warning
This method can only be called during a write transaction.
Declaration
Swift
public func swap(index1: Int, _ index2: Int)
Parameters
index1
The index of the object with which to replace the object at index
index2
.index2
The index of the object with which to replace the object at index
index1
.
-
Register 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.
This version of this method reports which of the objects in the List were added, removed, or modified in each write transaction as indices within the List. See the RealmCollectionChange documentation for more information on the change information supplied and an example of how to use it to update a UITableView.
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 source realm is read-only.Warning
This method can only be called on Lists which are stored on an Object which has been added to or retrieved from a Realm.
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 notifications 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 from startIndex by zero or more applications of successor().Declaration
Swift
public var endIndex: Int { return count }