Canceling NSInvocationOperation
Canceling NSInvocationOperation
- Subject: Canceling NSInvocationOperation
- From: Chase Latta <email@hidden>
- Date: Sat, 12 Feb 2011 12:43:26 -0800
Hello all,
I have run into a situation that I don't quite have a solution for. I
have a UIScrollView that holds a bunch of CALayers. My controller is
set up to check and see if it can cache layers that are offscreen
after the user scrolls a certain amount. I found that doing this on
the main thread was causing my scrolling to not be very smooth so I
decided to use NSInvocationOperations to figure out what can be cached
in an operation queue.
Everything is working fine but I am not sure how I deal with canceling
the operation. If I were subclassing NSOperation I would simply check
to see if [self isCancelled] returned true and go from there but if I
throw this into my method that I am passing to the
NSInvocationOperation I will just be calling this on my controller
object. I guess the root of my question is how do I access the
operation from within my method that I am passing to
initWithTarget:selector:object when I create my invocation operation?
I guess I could just create a subclass of NSOperation but I would like
to avoid this because I think it would be overkill.
---------------------------
// Some Code:
- (void)myOperationInController;
{
// Do stuff
if (![self isCancelled]) // <---- I need to access the operation
here, self refers to my controller
[self performSelectorOnMainThread...]
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
// Note: I am not creating an operation every time the user
scrolls in my actual application
NSInvocationOperation *op = [[NSInvocationOperation alloc]
initWithTarget:self selector:@selector(myOperationInController)
object:nil];
[self.oprationQueue addOperation:op];
[op release];
}
---------------------------
Thanks in advance,
Chase
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