---
title: dispatch_data_t
framework: dispatch
role: symbol
role_heading: Type Alias
path: dispatch/dispatch_data_t
---

# dispatch_data_t

An immutable object representing a contiguous or sparse region of memory.

## Declaration

```swift
typealias dispatch_data_t = __DispatchData
```

## Discussion

Discussion Any direct access to the memory in a dispatch data object must not modify that memory. In 64-bit apps, you may cast a dispatch_data_t type to an NSData object. However, you may not perform a reverse cast — that is, cast an NSData object to a dispatch_data_t type.