A type erased Projection.
ProjectionObservable is a Combine publisher
The Projection’s underlying type - a child of Realm Object or EmbeddedObject.
Swift
associatedtype Root : RLMObjectBaseThe object being projected
DeclarationSwift
var rootObject: Root { get }Registers a block to be called each time the projection’s underlying object changes.
The block will be asynchronously called after each write transaction which deletes the underlying object or modifies any of the projected properties of the object, including self-assignments that set a property to its existing value.
For write transactions performed on different threads or in different processes, the block will be called when the managing Realm is (auto)refreshed to a version including the changes, while for local write transactions it will be called at some point in the future after the write transaction is committed.
If no key paths are given, the block will be executed on any insertion, modification, or deletion for all projected properties, including projected 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 Person: Object {
@Persisted var firstName: String
@Persisted var lastName = ""
@Persisted public var friends: List<Person>
}
class PersonProjection: Projection<Person> {
@Projected(\Person.firstName) var name
@Projected(\Person.lastName.localizedUppercase) var lastNameCaps
@Projected(\Person.friends.projectTo.firstName) var firstFriendsName: ProjectedCollection<String>
}
let token = projectedPerson.observe(keyPaths: ["name"], { changes in
// ...
})
Person.firstName property of the the projection’s underlying Person Object, but not for any changes made to Person.lastName or Person.friends list.PersonProjection.name property, but not for another projection’s property change.If the observed key path were ["firstFriendsName"], then any insertion, deletion, or modification of the firstName of the friends list will trigger the block. A change to someFriend.lastName would not trigger the block (where someFriend is an element contained in friends)
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.
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.
Unlike with List and Results, there is no “initial” callback made after you add a new notification block.
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.
It is safe to capture a strong reference to the observed object within the callback block. There is no retain cycle due to that the callback is retained by the returned token and not by the object itself.
Warning
Warning
For projected properties where the original property has the same root property name, this will trigger a PropertyChange for each of the Projected properties even though the change only corresponds to one of them. For the following Projection object “`swift class PersonProjection: Projection { @Projected(\Person.firstName) var name @Projected(\Person.address.country) originCountry @Projected(\Person.address.phone.number) mobile }
let token = projectedPerson.observe { changes in
if case .change(_, let propertyChanges) = changes {
propertyChanges[0].newValue as? String, "Winterfell" // Will notify the new value
propertyChanges[1].newValue as? String, "555-555-555" // Will notify with the current value, which hasn't change.
}
})
try realm.write {
person.address.country = "Winterfell"
}
```
Swift
public func observe(keyPaths: [String]? = nil,
on queue: DispatchQueue? = nil,
_ block: @escaping (ObjectChange<Self>) -> Void) -> NotificationToken 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 projected property change on the object. String key paths which do not correspond to a valid projected property will throw an exception.
queue
The serial dispatch queue to receive notification on. If nil, notifications are delivered to the current thread.
block
The block to call with information about changes to the object.
Return ValueA token which must be held for as long as you want updates to be delivered.
Registers a block to be called each time the projection’s underlying object changes.
The block will be asynchronously called after each write transaction which deletes the underlying object or modifies any of the projected properties of the object, including self-assignments that set a property to its existing value.
For write transactions performed on different threads or in different processes, the block will be called when the managing Realm is (auto)refreshed to a version including the changes, while for local write transactions it will be called at some point in the future after the write transaction is committed.
If no key paths are given, the block will be executed on any insertion, modification, or deletion for all projected properties, including projected 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 Person: Object {
@Persisted var firstName: String
@Persisted var lastName = ""
@Persisted public var friends: List<Person>
}
class PersonProjection: Projection<Person> {
@Projected(\Person.firstName) var name
@Projected(\Person.lastName.localizedUppercase) var lastNameCaps
@Projected(\Person.friends.projectTo.firstName) var firstFriendsName: ProjectedCollection<String>
}
let token = projectedPerson.observe(keyPaths: [\PersonProjection.name], { changes in
// ...
})
firstName property of the Object, but not for any changes made to lastName or friends list.If the observed key path were [\PersonProjection.firstFriendsName], then any insertion, deletion, or modification of the firstName of the friends list will trigger the block. A change to someFriend.lastName would not trigger the block (where someFriend is an element contained in friends)
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.
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.
Unlike with List and Results, there is no “initial” callback made after you add a new notification block.
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.
It is safe to capture a strong reference to the observed object within the callback block. There is no retain cycle due to that the callback is retained by the returned token and not by the object itself.
Warning
DeclarationSwift
public func observe(keyPaths: [PartialKeyPath<Self>],
on queue: DispatchQueue? = nil,
_ block: @escaping (ObjectChange<Self>) -> Void) -> NotificationToken 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 projected property change on the object. String key paths which do not correspond to a valid projected property will throw an exception.
queue
The serial dispatch queue to receive notification on. If nil, notifications are delivered to the current thread.
block
The block to call with information about changes to the object.
Return ValueA token which must be held for as long as you want updates to be delivered.
Registers a block to be called each time the projection’s underlying object changes.
The block will be asynchronously called on the actor after each write transaction which deletes the underlying object or modifies any of the projected properties of the object, including self-assignments that set a property to its existing value.
For write transactions performed on different threads or in different processes, the block will be called when the managing Realm is (auto)refreshed to a version including the changes, while for local write transactions it will be called at some point in the future after the write transaction is committed.
If no key paths are given, the block will be executed on any insertion, modification, or deletion for all projected properties, including projected 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 Person: Object {
@Persisted var firstName: String
@Persisted var lastName = ""
@Persisted public var friends: List<Person>
}
class PersonProjection: Projection<Person> {
@Projected(\Person.firstName) var name
@Projected(\Person.lastName.localizedUppercase) var lastNameCaps
@Projected(\Person.friends.projectTo.firstName) var firstFriendsName: ProjectedCollection<String>
}
let token = projectedPerson.observe(keyPaths: ["name"], { changes in
// ...
})
Person.firstName property of the the projection’s underlying Person Object, but not for any changes made to Person.lastName or Person.friends list.PersonProjection.name property, but not for another projection’s property change.["firstFriendsName"], then any insertion, deletion, or modification of the firstName of the friends list will trigger the block. A change to someFriend.lastName would not trigger the block (where someFriend is an element contained in friends)Notifications are delivered to a function isolated to the given actor, on that actors executor. If the actor is performing blocking work, multiple notifications may be coalesced into a single notification.
Unlike with Collection notifications, there is no “Initial” notification and there is no gap between when this function returns and when changes will first be captured.
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
DeclarationSwift
@available(macOS 10.15, tvOS 13.0, iOS 13.0, watchOS 6.0, *)
public func observe<A: Actor>(
keyPaths: [String]? = nil, on actor: A,
_isolation: isolated (any Actor)? = #isolation,
_ block: @Sendable @escaping (isolated A, ObjectChange<Self>) -> Void
) async -> NotificationToken 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 projected property change on the object. String key paths which do not correspond to a valid projected property will throw an exception.
actor
The actor which notifications should be delivered on. The block is passed this actor as an isolated parameter, allowing you to access the actor synchronously from within the callback.
block
The block to call with information about changes to the object.
Return ValueA token which must be held for as long as you want updates to be delivered.
Registers a block to be called each time the projection’s underlying object changes.
The block will be asynchronously called on the actor after each write transaction which deletes the underlying object or modifies any of the projected properties of the object, including self-assignments that set a property to its existing value.
For write transactions performed on different threads or in different processes, the block will be called when the managing Realm is (auto)refreshed to a version including the changes, while for local write transactions it will be called at some point in the future after the write transaction is committed.
If no key paths are given, the block will be executed on any insertion, modification, or deletion for all projected properties, including projected 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 Person: Object {
@Persisted var firstName: String
@Persisted var lastName = ""
@Persisted public var friends: List<Person>
}
class PersonProjection: Projection<Person> {
@Projected(\Person.firstName) var name
@Projected(\Person.lastName.localizedUppercase) var lastNameCaps
@Projected(\Person.friends.projectTo.firstName) var firstFriendsName: ProjectedCollection<String>
}
let token = projectedPerson.observe(keyPaths: [\PersonProjection.name], { changes in
// ...
})
Person.firstName property of the the projection’s underlying Person Object, but not for any changes made to Person.lastName or Person.friends list.PersonProjection.name property, but not for another projection’s property change.[\.firstFriendsName], then any insertion, deletion, or modification of the firstName of the friends list will trigger the block. A change to someFriend.lastName would not trigger the block (where someFriend is an element contained in friends)Notifications are delivered to a function isolated to the given actor, on that actors executor. If the actor is performing blocking work, multiple notifications may be coalesced into a single notification.
Unlike with Collection notifications, there is no “Initial” notification and there is no gap between when this function returns and when changes will first be captured.
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
DeclarationSwift
@available(macOS 10.15, tvOS 13.0, iOS 13.0, watchOS 6.0, *)
public func observe<A: Actor>(
keyPaths: [PartialKeyPath<Self>], on actor: A,
_isolation: isolated (any Actor)? = #isolation,
_ block: @Sendable @escaping (isolated A, ObjectChange<Self>) -> Void
) async -> NotificationToken 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 projected property change on the object. String key paths which do not correspond to a valid projected property will throw an exception.
actor
The actor which notifications should be delivered on. The block is passed this actor as an isolated parameter, allowing you to access the actor synchronously from within the callback.
block
The block to call with information about changes to the object.
Return ValueA token which must be held for as long as you want updates to be delivered.
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