Submits a block object for execution on a dispatch queue and waits until that block completes.
- iOS 4.0+
- macOS 10.6+
- tvOS 9.0+
- watchOS 2.0+
The queue on which to submit the block. This parameter cannot be
The block to be invoked on the target dispatch queue. This parameter cannot be
Submits a block to a dispatch queue for synchronous execution. Unlike
dispatch, this function does not return until the block has finished. Calling this function and targeting the current queue results in deadlock.
dispatch, no retain is performed on the target queue. Because calls to this function are synchronous, it "borrows" the reference of the caller. Moreover, no
Block is performed on the block.
As an optimization, this function invokes the block on the current thread when possible.