DITPendingCollectionsOperation

@interface DITPendingCollectionsOperation : NSObject

These objects are returned when calling collections on DITStore.

They allow chaining of further collections-related functions. You can either call exec on the object to get an array of DITCollections as an immediate return value, or you can establish either a live query or a subscription, which both work over time.

A live query, established by calling observe, will notify you every time there’s a change in the collections that the device knows about.

A subscription, established by calling subscribe, will act as a signal to other peers that you would like to receive updates from them about the collections that they know about.

Calling observe will generate both a subscription and a live query at the same time.

If you’d like to only observe local changes then you can call observeLocal.

If you want to observe changes in such a way that you can signal when you’re ready for the live query to deliver a new update then you can call observeWithNextSignal or observeLocalWithNextSignal.

  • Limit the number of collections that get returned.

    Declaration

    Objective-C

    - (nonnull DITPendingCollectionsOperation *)limit:(int)limit;

    Parameters

    limit

    The maximum number of collections that will be returned.

    Return Value

    A DITPendingCollectionsOperation that you can chain further function calls to.

  • Offset the resulting set of collections.

    This is useful if you aren’t interested in the first N collections for one reason or another. For example, you might already have obtained the first 20 collections and so you might want to get the next 20 collections, and that is when you would use offset.

    Declaration

    Objective-C

    - (nonnull DITPendingCollectionsOperation *)offset:(uint)offset;

    Parameters

    offset

    The number of collections that you want the eventual resulting set of collections to be offset by (and thus not include).

    Return Value

    A DITPendingCollectionsOperation that you can chain further function calls to.

  • Sort the collections based on a property of the collection.

    Declaration

    Objective-C

    - (nonnull DITPendingCollectionsOperation *)sort:(nonnull NSString *)query
                                       direction:(DITSortDirection)direction;

    Parameters

    query

    The query specifies the logic to be used when sorting the collections.
    direction

    Specify whether you want the sorting order to be ascending or descending.

    Return Value

    A DITPendingCollectionsOperation that you can chain further function calls to.

  • Return the list of collections requested based on the preceding function chaining.

    Declaration

    Objective-C

    - (nonnull NSArray<DITCollection *> *)exec;

    Return Value

    A list of DITCollectionss based on the preceding function chaining.

  • Subscribes the device to updates about collections that other devices know about.

    The returned DITSubscription object must be kept in scope for as long as you want to keep receiving updates.

    Declaration

    Objective-C

    - (nonnull DITSubscription *)subscribe;

    Return Value

    A DITSubscription object that must be kept in scope for as long as you want to keep receiving updates from other devices about the collections that they know about.

  • Enables you to subscribe to updates about collections that other devices know about, and have a block called when an update is received either locally or remotely.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)observe:
    (nonnull void (^)(DITCollectionsEvent *_Nonnull))eventHandler;

    Parameters

    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections that other devices know about, and have a block called when an update is received either locally or remotely.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)
    observeWithDeliveryQueue:(nonnull dispatch_queue_t)dispatchQueue
                eventHandler:(nonnull void (^)(DITCollectionsEvent *_Nonnull))
                                 eventHandler;

    Parameters

    dispatchQueue

    The dispatch queue that will be used to deliver updates. Defaults to the main queue.
    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections that other devices know about, and have a block called when an update is received either locally or remotely. You wont receive any further callbacks until you explicitly signal that you are ready for the next event to be delivered.

    This is a power-user API. If you’re unsure about which to use, you should probably default to using the simpler observe: API.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)observeWithNextSignal:
    (nonnull void (^)(DITCollectionsEvent *_Nonnull,
                      DittoSignalNextBlock _Nonnull))eventHandler;

    Parameters

    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections that other devices know about, and have a block called when an update is received either locally or remotely. You wont receive any further callbacks until you explicitly signal that you are ready for the next event to be delivered.

    This is a power-user API. If you’re unsure about which to use, you should probably default to using the simpler observe: API.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)
    observeWithNextSignalAndDeliveryQueue:
        (nonnull dispatch_queue_t)dispatchQueue
                             eventHandler:(nonnull void (^)(
                                              DITCollectionsEvent *_Nonnull,
                                              DittoSignalNextBlock _Nonnull))
                                              eventHandler;

    Parameters

    dispatchQueue

    The dispatch queue that will be used to deliver live query updates. Defaults to the main queue.
    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections local to this device.

    This won’t subscribe to receive updates from other devices and so it will only fire when a local change to the known collections occurs. If you want to receive remote updates as well then use observe or call subscribe.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)observeLocal:
    (nonnull void (^)(DITCollectionsEvent *_Nonnull))eventHandler;

    Parameters

    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections local to this device.

    This won’t subscribe to receive updates from other devices and so it will only fire when a local change to the known collections occurs. If you want to receive remote updates as well then use observe or call subscribe.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)
    observeLocalWithDeliveryQueue:(nonnull dispatch_queue_t)dispatchQueue
                     eventHandler:
                         (nonnull void (^)(DITCollectionsEvent *_Nonnull))
                             eventHandler;

    Parameters

    dispatchQueue

    The dispatch queue that will be used to deliver live query updates. Defaults to the main queue.
    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections local to this device.

    This won’t subscribe to receive updates from other devices and so it will only fire when a local change to the known collections occurs. If you want to receive remote updates as well then use observe or call subscribe.

    You wont receive any further callbacks until you explicitly signal that you are ready for the next event to be delivered.

    This is a power-user API. If you’re unsure about which to use, you should probably default to using the simpler observe: API.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)observeLocalWithNextSignal:
    (nonnull void (^)(DITCollectionsEvent *_Nonnull,
                      DittoSignalNextBlock _Nonnull))eventHandler;

    Parameters

    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.

  • Enables you to subscribe to updates about collections local to this device.

    This won’t subscribe to receive updates from other devices and so it will only fire when a local change to the known collections occurs. If you want to receive remote updates as well then use observe or call subscribe.

    You wont receive any further callbacks until you explicitly signal that you are ready for the next event to be delivered.

    This is a power-user API. If you’re unsure about which to use, you should probably default to using the simpler observe: API.

    The returned DITLiveQuery object must be kept in scope for as long as you want the provided eventHandler to be called when an update occurs.

    Declaration

    Objective-C

    - (nonnull DITLiveQuery *)
    observeLocalWithNextSignalAndDeliveryQueue:
        (nonnull dispatch_queue_t)dispatchQueue
                                  eventHandler:
                                      (nonnull void (^)(
                                          DITCollectionsEvent *_Nonnull,
                                          DittoSignalNextBlock _Nonnull))
                                          eventHandler;

    Parameters

    dispatchQueue

    The dispatch queue that will be used to deliver live query updates. Defaults to the main queue.
    eventHandler

    A block that will be called every time there is an update about the list of known about collections.

    Return Value

    A DITLiveQuery object that must be kept in scope for as long as you want to keep receiving updates.