At 12:14 PM -0800 1/27/12, Jens Alfke wrote:
I'm really used to using
-performSelector:withObject:afterDelay: to make
something happen later. But I'd much rather use
a block than a target/action. I can't find any
API for this, however. Am I missing something?
What I want is basically like
PerformBlockAfterDelay(^{ code here}, 5.0);
Me too! PerformBlockOnThread would be nice as well.
It looks like I should just call dispatch_async,
but I'm unsure which dispatch queue to use.
dispatch_get_main_queue only works for the main
thread. Can I use dispatch_get_current_queue?
As others have mentioned later in the thread,
with the exception of the main queue, dispatch
queues aren't tied to threads -- they execute
blocks on a pool of threads managed by the system.
Later in the thread:
At 6:00 PM +1100 1/28/12, Shane Stanley wrote:
On 28/01/2012, at 1:41 PM, Ken Thomases wrote:
Believe it or not, this also works:
> [(id)^{ ... code here ... }
performSelector:@selector(invoke) withObject:nil
afterDelay:5.0];
That is, you can target
performSelector:withObject:afterDelay: at a
block, itself, rather than some other helper
object. And, a block implements the -invoke
selector to, well, invoke itself.
FWIW, on stackoverflow there's a post suggesting
the use of a block as a target, and using
-invoke to select it. In the comments is one
from bbum from last October:
This "works" by coincidence. It relies on
private API; the invoke method on Block objects
is not public and not intended to be used in
this fashion.
<http://stackoverflow.com/questions/4581782/can-i-pass-a-block-as-a-selector-with-objective-c>,
about fourth answer down.
This reminds me that, IIRC, a block (after it's
copied to the heap) _is_ an object. I was going
to suggest some form of calling BlockCopy
manually, but given the example above, you might
something like:
-(void)executeBlock:((^)(void) block // <- someone help with this declaration
{
block();
}
...
[self performSelector:@selector(executeBlock:)
withObject:(id)^{ ... code here ... }
afterDelay:5.0];
might work.
I'm still trying to get my head around all these
issues as well, but hoping this might help you to
a solution. I'm interested in the solution as
well.
HTH,
-Steve
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