RealmKeyedCollection
public protocol RealmKeyedCollection : ThreadConfined, CustomStringConvertible, Sequence
A homogenous key-value collection of Object
s which can be retrieved, filtered, sorted, and operated upon.
-
The type of key associated with this collection
Declaration
Swift
associatedtype Key : _MapKey
-
The type of value associated with this collection.
Declaration
Swift
associatedtype Value : RealmCollectionValue
-
The Realm which manages the map, or
nil
if the map is unmanaged.Declaration
Swift
var realm: Realm? { get }
-
Indicates if the map can no longer be accessed.
Declaration
Swift
var isInvalidated: Bool { get }
-
Returns the number of key-value pairs in this map.
Declaration
Swift
var count: Int { get }
-
A human-readable description of the objects contained in the Map.
Declaration
Swift
var description: String { get }
-
Updates the value stored in the dictionary for the given key, or adds a new key-value pair if the key does not exist.
Note
Note:If the value being added to the dictionary is an unmanaged object and the dictionary is managed then that unmanaged object will be added to the Realm.
Warning
This method may only be called during a write transaction.
Parameters
value
a value’s key path predicate.
forKey
The direction to sort in.
-
Removes the given key and its associated object, only if the key exists in the dictionary. If the key does not exist, the dictionary will not be modified.
Warning
This method may only be called during a write transaction.Declaration
Swift
func removeObject(for key: Key)
-
Removes all objects from the dictionary. The objects are not removed from the Realm that manages them.
Warning
This method may only be called during a write transaction.Declaration
Swift
func removeAll()
-
Returns the value for a given key, or sets a value for a key should the subscript be used for an assign.
Note
Note:If the value being added to the dictionary is an unmanaged object and the dictionary is managed then that unmanaged object will be added to the Realm.
Note
Note:If the value being assigned for a key is
nil
then that key will be removed from the dictionary.Warning
This method may only be called during a write transaction.
Parameters
key
The key.
-
Returns a type of
Value
for a specified key if it exists in the map.Note that when using key-value coding, the key must be a string.
Declaration
Swift
func value(forKey key: String) -> AnyObject?
Parameters
key
The key to the property whose values are desired.
-
Returns a type of
Value
for a specified key if it exists in the map.Declaration
Swift
func value(forKeyPath keyPath: String) -> AnyObject?
Parameters
keyPath
The key to the property whose values are desired.
-
Adds a given key-value pair to the dictionary or updates a given key should it already exist.
Warning
This method can only be called during a write transaction.
Declaration
Swift
func setValue(_ value: Any?, forKey key: String)
Parameters
value
The object value.
key
The name of the property whose value should be set on each object.
-
Returns a
Results
containing all matching values in the dictionary with the given predicate.Note
This will return the values in the dictionary, and not the key-value pairs.
Parameters
predicate
The predicate with which to filter the values.
-
Returns a Boolean value indicating whether the Map contains the key-value pair satisfies the given predicate
Declaration
Parameters
where
a closure that test if any key-pair of the given map represents the match.
-
Returns a
Results
containing the objects in the dictionary, but sorted.Objects are sorted based on their values. For example, to sort a dictionary of
Date
s from neweset to oldest based, you might calldates.sorted(ascending: true)
.Parameters
ascending
The direction to sort in.
-
Returns a
Results
containing the objects in the dictionary, but sorted.Objects are sorted based on the values of the given key path. For example, to sort a dictionary of
Student
s from youngest to oldest based on theirage
property, you might callstudents.sorted(byKeyPath: "age", ascending: true)
.Warning
Dictionaries may only be sorted by properties of boolean,
Date
,NSDate
, single and double-precision floating point, integer, and string types.Parameters
keyPath
The key path to sort by.
ascending
The direction to sort in.
-
Returns a
Results
containing the objects in the dictionary, but sorted.Warning
Dictionaries may only be sorted by properties of boolean,
Date
,NSDate
, single and double-precision floating point, integer, and string types.Declaration
Swift
func sorted<S: Sequence>(by sortDescriptors: S) -> Results<Value> where S.Iterator.Element == SortDescriptor
-
Returns all of the keys in this dictionary.
Declaration
Swift
var keys: [Key] { get }
-
Returns all of the values in the dictionary.
Declaration
Swift
var values: [Value] { get }
-
Returns the minimum (lowest) value of the given property among all the objects in the collection, or
nil
if the dictionary is empty.Warning
Only a property whose type conforms to the
MinMaxType
protocol can be specified.Declaration
Swift
func min<T>(ofProperty property: String) -> T? where T : _HasPersistedType, T.PersistedType : MinMaxType
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 dictionary, or
nil
if the dictionary is empty.Warning
Only a property whose type conforms to the
MinMaxType
protocol can be specified.Declaration
Swift
func max<T>(ofProperty property: String) -> T? where T : _HasPersistedType, T.PersistedType : MinMaxType
Parameters
property
The name of a property whose minimum value is desired.
-
Returns the sum of the given property for objects in the dictionary, or
nil
if the dictionary is empty.Warning
Only names of properties of a type conforming to the
AddableType
protocol can be used.Declaration
Swift
func sum<T>(ofProperty property: String) -> T where T : _HasPersistedType, T.PersistedType : AddableType
Parameters
property
The name of a property conforming to
AddableType
to calculate sum on. -
Returns the average value of a given property over all the objects in the dictionary, or
nil
if the dictionary is empty.Warning
Only a property whose type conforms to the
AddableType
protocol can be specified.Declaration
Swift
func average<T>(ofProperty property: String) -> T? where T : _HasPersistedType, T.PersistedType : AddableType
Parameters
property
The name of a property whose values should be summed.
-
observe(keyPaths:
Default implementationon: _: ) Registers a block to be called each time the dictionary changes.
The block will be asynchronously called with the initial dictionary, and then called again after each write transaction which changes either any of the keys or values in the dictionary.
The
change
parameter that is passed to the block reports, in the form of keys within the dictionary, which of the key-value pairs were added, removed, or modified during each write transaction.At the time when the block is called, the dictionary 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.If no queue is given, notifications are delivered via the standard run loop, and so can’t be delivered while the run loop is blocked by other activity. If a queue is given, notifications are delivered to that queue instead. 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 myStringMap = myObject.stringMap print("myStringMap.count: \(myStringMap?.count)") // => 0 let token = myStringMap.observe { changes in switch changes { case .initial(let myStringMap): // Will print "myStringMap.count: 1" print("myStringMap.count: \(myStringMap.count)") print("Dog Name: \(myStringMap["nameOfDog"])") // => "Rex" break case .update: // Will not be hit in this example break case .error: break } } try! realm.write { myStringMap["nameOfDog"] = "Rex" } // end of run loop execution context
If no key paths are given, the block will be executed on any insertion, modification, or deletion for all object properties and the properties of any nested, linked objects. If a key path or key paths are provided, then the block will be called for changes which occur only on the provided key paths. For example, if:
class Dog: Object { @Persisted var name: String @Persisted var age: Int @Persisted var toys: List<Toy> } // ... let dogs = myObject.mapOfDogs let token = dogs.observe(keyPaths: ["name"]) { changes in switch changes { case .initial(let dogs): // ... case .update: // This case is hit: // - after the token is initialized // - when the name property of an object in the // collection is modified // - when an element is inserted or removed // from the collection. // This block is not triggered: // - when a value other than name is modified on // one of the elements. case .error: // ... } } // end of run loop execution context
- If the observed key path were
["toys.brand"]
, then any insertion or deletion to thetoys
list on any of the collection’s elements would trigger the block. Changes to thebrand
value on anyToy
that is linked to aDog
in this collection will trigger the block. Changes to a value other thanbrand
on anyToy
that is linked to aDog
in this collection would not trigger the block. Any insertion or removal to theDog
type collection being observed would also trigger a notification. If the above example observed the
["toys"]
key path, then any insertion, deletion, or modification to thetoys
list for any element in the collection would trigger the block. Changes to any value on anyToy
that is linked to aDog
in this collection would not trigger the block. Any insertion or removal to theDog
type collection being observed would still trigger a notification.
Note
Multiple notification tokens on the same object which filter for separate key paths do not filter exclusively. If one key path change is satisfied for one notification token, then all notification token blocks for that object will execute.
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.
Note
The keyPaths parameter refers to object properties of the collection type and does not refer to particular key/value pairs within the collection.
Default Implementation
Declaration
Swift
func observe(keyPaths: [String]?, on queue: DispatchQueue?, _ block: @escaping (RealmMapChange<Self>) -> Void) -> NotificationToken
Parameters
keyPaths
Only properties contained in the key paths array will trigger the block when they are modified. If
nil
, notifications will be delivered for any property change on the object. String key paths which do not correspond to a valid a property will throw an exception. See description above for more detail on linked properties.queue
The serial dispatch queue to receive notification on. If
nil
, notifications are delivered to the current thread.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.
- If the observed key path were
-
Returns if this collection is frozen
Declaration
Swift
var isFrozen: Bool { get }
-
Returns a frozen (immutable) snapshot of this collection.
The frozen copy is an immutable collection which contains the same data as this collection currently contains, but will not update when writes are made to the containing Realm. Unlike live collections, frozen collections can be accessed from any thread.
Warning
This method cannot be called during a write transaction, or when the containing Realm is read-only.Warning
Holding onto a frozen collection for an extended period while performing write transaction on the Realm may result in the Realm file growing to large sizes. SeeRealm.Configuration.maximumNumberOfActiveVersions
for more information.Declaration
Swift
func freeze() -> Self
-
Returns a live (mutable) version of this frozen collection.
This method resolves a reference to a live copy of the same frozen collection. If called on a live collection, will return itself.
Declaration
Swift
func thaw() -> Self?
-
objectWillChange
Extension methodA publisher that emits Void each time the collection changes.
Despite the name, this actually emits after the collection has changed.
Declaration
Swift
public var objectWillChange: RealmPublishers.WillChange<Self> { get }
-
collectionPublisher
Extension methodA publisher that emits the collection each time the collection changes.
Declaration
Swift
public var collectionPublisher: RealmPublishers.Value<Self> { get }
-
collectionPublisher(keyPaths:
Extension method) A publisher that emits the collection each time the collection changes on the given property keyPaths.
Declaration
Swift
public func collectionPublisher(keyPaths: [String]?) -> RealmPublishers.Value<Self>
-
changesetPublisher
Extension methodA publisher that emits a collection changeset each time the collection changes.
Declaration
Swift
public var changesetPublisher: RealmPublishers.MapChangeset<Self> { get }
-
changesetPublisher(keyPaths:
Extension method) A publisher that emits a collection changeset each time the collection changes on the given property keyPaths.
Declaration
Swift
public func changesetPublisher(keyPaths: [String]?) -> RealmPublishers.MapChangeset<Self>
-
min(of:
Extension method) 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
func min<T>(of keyPath: KeyPath<Value.Wrapped, T>) -> T? where T : _HasPersistedType, T.PersistedType : MinMaxType
Parameters
keyPath
The keyPath of a property whose minimum value is desired.
-
max(of:
Extension method) 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
func max<T>(of keyPath: KeyPath<Value.Wrapped, T>) -> T? where T : _HasPersistedType, T.PersistedType : MinMaxType
Parameters
keyPath
The keyPath of a property whose minimum value is desired.
-
sum(of:
Extension method) Returns the sum of the given property for objects in the collection, or
nil
if the collection is empty.Warning
Only names of properties of a type conforming to the
AddableType
protocol can be used.Declaration
Swift
func sum<T>(of keyPath: KeyPath<Value.Wrapped, T>) -> T where T : _HasPersistedType, T.PersistedType : AddableType
Parameters
keyPath
The keyPath of a property conforming to
AddableType
to calculate sum on. -
average(of:
Extension method) Returns the average value of a given property over all the objects in the collection, or
nil
if the collection is empty.Warning
Only a property whose type conforms to the
AddableType
protocol can be specified.Declaration
Swift
func average<T>(of keyPath: KeyPath<Value.Wrapped, T>) -> T? where T : _HasPersistedType, T.PersistedType : AddableType
Parameters
keyPath
The keyPath of a property whose values should be summed.
Available where Value
: OptionalProtocol
, Value.Wrapped
: ObjectBase
, Value.Wrapped
: RealmCollectionValue
-
sorted(by:
Extension methodascending: ) 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
func sorted<T>(by keyPath: KeyPath<Value.Wrapped, T>, ascending: Bool) -> Results<Value> where T : _HasPersistedType, T.PersistedType : SortableType
Parameters
keyPath
The key path to sort by.
ascending
The direction to sort in.
-
min()
Extension methodReturns the minimum (lowest) value of the collection, or
nil
if the collection is empty.Declaration
Swift
func min() -> Value?
-
max()
Extension methodReturns the maximum (highest) value of the collection, or
nil
if the collection is empty.Declaration
Swift
func max() -> Value?
-
sum()
Extension methodReturns the sum of the values in the collection, or
nil
if the collection is empty.Declaration
Swift
func sum() -> Value
-
average()
Extension methodReturns the average of all of the values in the collection.
Declaration
Swift
func average<T>() -> T? where T : _HasPersistedType, T.PersistedType : AddableType
-
sorted(ascending:
Default implementation) Default Implementation
Returns a
Results
containing the objects in the collection, but sorted.Objects are sorted based on their values. For example, to sort a collection of
Date
s from neweset to oldest based, you might calldates.sorted(ascending: true)
.Parameters
ascending
The direction to sort in.