cancel dispatch_after() method? [duplicate]

Answer 1

OK, so, with all answers collected, and possible solutions, seems like the best one for this case (preserving simplicity) is calling performSelector:withObject:afterDelay: and cancelling it with cancelPreviousPerformRequestsWithTarget: call when desired. In my case - just before scheduling next delayed call:

[NSObject cancelPreviousPerformRequestsWithTarget: self selector:@selector(myDelayedMethod) object: self];

[self performSelector:@selector(myDelayedMethod) withObject: self afterDelay: desiredDelay];

Answer 2

Use a dispatch timer source (that is what dispatch_after uses internally anyway).

A dispatch timer source can be canceled or its timer parameters changed after creation.

Answer 3

There is NO way to prevent a dispatch_block from executing once it has been dispatch to it's queue, meaning that your dispatch_after cannot be canceled. Only option is to add in your block a condition to be checked at runtime to prevent execution. ie.

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^ {
if(self.shouldExecuteDispatchBlock)
{ // do your stuff }  });

Answer 4

For this purpose i used this class:

https://github.com/SebastienThiebaud/dispatch_cancelable_block

you can call a cancel() function to revoke the execution of what's in the block.