Is there any way to implement dispatch_cancel()?

Question

So far I have gone through the doc of GCD, however it seems there misses dispatch_cancel() which I want to use it to cancel all dispatch\'s blocks invocation. Is there any w

Answer 1

from iOS 8 and higher you can cancel block execution with
dispatch_block_cancel

dispatch_block_t blockTask = dispatch_block_create(0,{
 //do some task
});
dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW,5*NSEC_PER_SEC);
dispatch_after(time,dispatch_get_main_queue(),blockTask);

dispatch_block_cancel(blockTask);