# Dispatch Data An object that manages a memory-based data buffer and exposes it as a contiguous block of memory. ## Discussion The memory buffer managed by this object may be a single contiguous block of memory, or it may consist of multiple discontiguous blocks. For the discontiguous case, the dispatch data object makes it appear as if the memory is contiguous. ## Topics ### Creating a Dispatch Data Object [`extern dispatch_data_tdispatch_data_create(const void *buffer, size_t size, dispatch_queue_t queue, dispatch_block_t destructor);`](/documentation/Dispatch/dispatch_data_create) Creates a new dispatch data object with the specified memory buffer. [`extern dispatch_data_tdispatch_data_create_map(dispatch_data_t data, const void **buffer_ptr, size_t *size_ptr);`](/documentation/Dispatch/dispatch_data_create_map) Returns a new dispatch data object containing a contiguous representation of the specified object’s memory. [`extern dispatch_data_tdispatch_data_create_concat(dispatch_data_t data1, dispatch_data_t data2);`](/documentation/Dispatch/dispatch_data_create_concat) Returns a new dispatch data object consisting of the concatenated data from two other data objects. [`extern dispatch_data_tdispatch_data_create_subrange(dispatch_data_t data, size_t offset, size_t length);`](/documentation/Dispatch/dispatch_data_create_subrange) Returns a new dispatch data object whose contents consist of a portion of another object’s memory region. [`extern dispatch_data_tdispatch_data_copy_region(dispatch_data_t data, size_t location, size_t *offset_ptr);`](/documentation/Dispatch/dispatch_data_copy_region) Returns a data object containing a portion of the data in another data object. [`#define dispatch_data_empty`](/documentation/Dispatch/dispatch_data_empty) A dispatch data object representing a zero-length memory region. [`typealias dispatch_data_t`](/documentation/Dispatch/dispatch_data_t) An immutable object representing a contiguous or sparse region of memory. [`@protocol OS_dispatch_data `](/documentation/Dispatch/OS_dispatch_data) [`#define DISPATCH_DATA_DESTRUCTOR_DEFAULT`](/documentation/Dispatch/DISPATCH_DATA_DESTRUCTOR_DEFAULT) The default data destructor for dispatch objects. [`#define DISPATCH_DATA_DESTRUCTOR_FREE`](/documentation/Dispatch/DISPATCH_DATA_DESTRUCTOR_FREE) The destructor for dispatch data objects whose memory buffer was created using the malloc family of allocation routines. ### Getting the Number of Elements [`extern size_t dispatch_data_get_size(dispatch_data_t data);`](/documentation/Dispatch/dispatch_data_get_size) Returns the logical size of the memory managed by a dispatch data object ### Applying Changes to the Data [`extern bool dispatch_data_apply(dispatch_data_t data, dispatch_data_applier_t applier);`](/documentation/Dispatch/dispatch_data_apply) Traverses the memory of a dispatch data object and executes custom code on each region. [`typedef _Bool (^)(NSObject *, unsigned long, const void *, unsigned long) dispatch_data_applier_t;`](/documentation/Dispatch/dispatch_data_applier_t) A block to invoke for every contiguous memory region in a data object. --- 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)