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

# dispatch_source_type_t

An identifier for the type of system object being monitored by a dispatch source.

## Declaration

```occ
typedef const struct dispatch_source_type_s * dispatch_source_type_t;
```

## Discussion

Discussion Constants of this type represent the class of low-level system object that is being monitored by the dispatch source. Constants of this type are passed as a parameter to dispatch_source_create and determine how the handle argument is interpreted (as a file descriptor, mach port, signal number, process identifier, etc.) and how the mask argument is interpreted.

## Topics

### Dispatch Source Types

- [DISPATCH_SOURCE_TYPE_TIMER](dispatch/dispatch_source_type_timer.md)
- [DISPATCH_SOURCE_TYPE_READ](dispatch/dispatch_source_type_read.md)
- [DISPATCH_SOURCE_TYPE_WRITE](dispatch/dispatch_source_type_write.md)
- [DISPATCH_SOURCE_TYPE_VNODE](dispatch/dispatch_source_type_vnode.md)
- [DISPATCH_SOURCE_TYPE_SIGNAL](dispatch/dispatch_source_type_signal.md)
- [DISPATCH_SOURCE_TYPE_PROC](dispatch/dispatch_source_type_proc.md)
- [DISPATCH_SOURCE_TYPE_MEMORYPRESSURE](dispatch/dispatch_source_type_memorypressure.md)
- [DISPATCH_SOURCE_TYPE_MACH_SEND](dispatch/dispatch_source_type_mach_send.md)
- [DISPATCH_SOURCE_TYPE_MACH_RECV](dispatch/dispatch_source_type_mach_recv.md)
- [DISPATCH_SOURCE_TYPE_DATA_ADD](dispatch/dispatch_source_type_data_add.md)
- [DISPATCH_SOURCE_TYPE_DATA_OR](dispatch/dispatch_source_type_data_or.md)

## See Also

### Creating a Dispatch Source

- [dispatch_source_create](dispatch/dispatch_source_create.md)
- [dispatch_source_t](dispatch/dispatch_source_t.md)