Submits a block for asynchronous execution on a dispatch queue and returns immediately.
- iOS 4.0+
- macOS 10.6+
- tvOS 9.0+
- watchOS 2.0+
The queue on which to submit the block. The queue is retained by the system until the block has run to completion. This parameter cannot be
The block to submit to the target dispatch queue. This function performs
Blockon behalf of callers. This parameter cannot be
This function is the fundamental mechanism for submitting blocks to a dispatch queue. Calls to this function always return immediately after the block has been submitted and never wait for the block to be invoked. The target queue determines whether the block is invoked serially or concurrently with respect to other blocks submitted to that same queue. Independent serial queues are processed concurrently with respect to each other.