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.

Properties

  • Element type contained in this collection.

    Declaration

    Swift

    public typealias Element = T
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  • Returns the object at the given index on get. Replaces the object at the given index 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.

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  • 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?
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  • Indicates if the List can no longer be accessed.

    Declaration

    Swift

    public var invalidated: Bool { return _rlmArray.invalidated }
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Initializers

Index Retrieval

  • 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.

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  • 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.

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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 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.

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Object Retrieval

  • Returns the first object in the List, or nil if empty.

    Declaration

    Swift

    public var first: T? { return _rlmArray.firstObject() as! T? }
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  • Returns the last object in the List, or nil if empty.

    Declaration

    Swift

    public var last: T? { return _rlmArray.lastObject() as! T? }
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KVC

  • 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.

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  • 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.
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Filtering

  • 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.

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  • Returns Results containing elements that match the given predicate.

    Declaration

    Swift

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

    Parameters

    predicate

    The predicate to filter the objects.

    Return Value

    Results containing elements that match the given predicate.

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Sorting

  • 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.

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  • 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

    SortDescriptors to sort by.

    Return Value

    Results with elements sorted by the given sort descriptors.

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Aggregate Operations

  • 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.

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  • 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.

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  • 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.

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  • 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.

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Mutation

  • 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.
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  • 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.
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  • 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.
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  • 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.
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  • 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()
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  • 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()
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  • 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.
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  • 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.
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  • 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.
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Notifications

  • 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. You must retain the returned token for as long as you want the results to continue to be sent to the block. To stop receiving updates, call stop() on the token.

    Declaration

    Swift

    public func addNotificationBlock(block: (List<T>) -> ()) -> 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.

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Sequence Support

  • Returns a GeneratorOf<T> that yields successive elements in the List.

    Declaration

    Swift

    public func generate() -> RLMGenerator<T>
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RangeReplaceableCollection Support

  • Replace the given subRange of elements with newElements.

    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.
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  • 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 }
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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 { return count }
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