Submits an application-defined function for asynchronous execution on a dispatch queue and returns immediately.
- iOS 4.0+
- macOS 10.6+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
The queue on which to submit the function. The queue is retained by the system until the function has run to completion. This parameter cannot be
The application-defined context parameter to pass to the function.
The application-defined function to invoke on the target queue. The first parameter passed to this function is the value of the
contextparameter. This parameter cannot be
This function is the fundamental mechanism for submitting application-defined functions to a dispatch queue. Calls to this function always return immediately after the function has been submitted and never wait for it to be invoked. The target queue determines whether the function is invoked serially or concurrently with respect to other tasks submitted to that same queue. Serial queues are processed concurrently with respect to each other.