# DispatchSourceProtocol Defines a common set of properties and methods that are shared with all dispatch source types. ``` protocol DispatchSourceProtocol : NSObjectProtocol ``` ## Overview You do not adopt this protocol in your objects. Instead, use the [`makeSignalSource(signal:queue:)`](/documentation/Dispatch/DispatchSource/makeSignalSource(signal:queue:)) method to create an object that adopts this protocol. ## Topics ### Activating, Suspending, and Resuming a Source [`activate()`](/documentation/Dispatch/DispatchSourceProtocol/activate()) Activates the dispatch source. [`suspend()`](/documentation/Dispatch/DispatchSourceProtocol/suspend()) Suspends the dispatch source. [`resume()`](/documentation/Dispatch/DispatchSourceProtocol/resume()) Resumes the dispatch source. ### Canceling a Dispatch Source [`cancel()`](/documentation/Dispatch/DispatchSourceProtocol/cancel()) Asynchronously cancels the dispatch source, preventing any further invocation of its event handler block. [`isCancelled`](/documentation/Dispatch/DispatchSourceProtocol/isCancelled) Returns a Boolean indicating whether the given dispatch source has been canceled. [`setCancelHandler(handler:)`](/documentation/Dispatch/DispatchSourceProtocol/setCancelHandler(handler:)) Sets the cancellation handler block for the dispatch source. [`setCancelHandler(qos:flags:handler:)`](/documentation/Dispatch/DispatchSourceProtocol/setCancelHandler(qos:flags:handler:)) Sets the cancellation handler block for the dispatch source with the specified quality-of-service class and work item options. ### Installing Event Handlers [`setEventHandler(handler:)`](/documentation/Dispatch/DispatchSourceProtocol/setEventHandler(handler:)) Sets the event handler work item for the dispatch source. [`setEventHandler(qos:flags:handler:)`](/documentation/Dispatch/DispatchSourceProtocol/setEventHandler(qos:flags:handler:)) [`setRegistrationHandler(handler:)`](/documentation/Dispatch/DispatchSourceProtocol/setRegistrationHandler(handler:)) Sets the registration handler work item for the dispatch source. [`setRegistrationHandler(qos:flags:handler:)`](/documentation/Dispatch/DispatchSourceProtocol/setRegistrationHandler(qos:flags:handler:)) [`DispatchSourceHandler`](/documentation/Dispatch/DispatchSourceProtocol/DispatchSourceHandler) ### Getting the Dispatch Source Attributes [`handle`](/documentation/Dispatch/DispatchSourceProtocol/handle) Returns the underlying system handle associated with the specified dispatch source. [`data`](/documentation/Dispatch/DispatchSourceProtocol/data) Returns pending data for the dispatch source. [`mask`](/documentation/Dispatch/DispatchSourceProtocol/mask) Returns the mask of events monitored by the dispatch source. ## Relationships ### Inherited By [`DispatchSourceWrite`](/documentation/Dispatch/DispatchSourceWrite) [`DispatchSourceUserDataOr`](/documentation/Dispatch/DispatchSourceUserDataOr) [`DispatchSourceMachReceive`](/documentation/Dispatch/DispatchSourceMachReceive) [`DispatchSourceTimer`](/documentation/Dispatch/DispatchSourceTimer) [`DispatchSourceProcess`](/documentation/Dispatch/DispatchSourceProcess) [`DispatchSourceRead`](/documentation/Dispatch/DispatchSourceRead) [`DispatchSourceMemoryPressure`](/documentation/Dispatch/DispatchSourceMemoryPressure) [`DispatchSourceUserDataAdd`](/documentation/Dispatch/DispatchSourceUserDataAdd) [`DispatchSourceMachSend`](/documentation/Dispatch/DispatchSourceMachSend) [`DispatchSourceUserDataReplace`](/documentation/Dispatch/DispatchSourceUserDataReplace) [`DispatchSourceFileSystemObject`](/documentation/Dispatch/DispatchSourceFileSystemObject) [`DispatchSourceSignal`](/documentation/Dispatch/DispatchSourceSignal) ### Conforming Types [`DispatchSource`](/documentation/Dispatch/DispatchSource) ### Inherits From [`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)