Question

I have a calculation task that will take some time to complete. Minutes. Maybe several minutes. I want to launch the task with a button on the UI, then return to the UI so that the user can interact with other areas while the task is running.

I modeled my code after an example from Apple’s Concurrency Programming Guide:

// code here to initialize the c++ objects a, b, c, and d as ivars.

- (NSOperation*)taskWithData:(id)data 
{
    NSInvocationOperation* theOp = [[[NSInvocationOperation alloc] 
                                        initWithTarget:self
                                        selector:@selector(myTaskMethod:) 
                                        object:nil] autorelease];
       return theOp;
}

// This is the method that does the actual work of the task.
- (void)myTaskMethod:(id)data 
{
    // Perform the task.
    task(a, b, c, d);
}

Then I call myTaskMethod:data from within the button’s IBAction:

-(void)actionButtonPushed:(id)sender
{
    NSAutoreleasePool* myPool = [NSAutoreleasePool alloc] init];
    [self myTaskMethod:nil];
    [myPool drain];
}

I hoped that control would return to the UI, but it doesn’t. We don’t return to the UI until myTaskMethod: finishes its business … exactly the same behavior as if I called task() directly in the IBAction code.

More details: this code is Objective-C++ (.mm), and task(); is a c++ function.

If it’s not obvious, this is my first attempt at using Concurrency; I need some direction, please.

tia, g

Update: Fixed. I had neglected to create an SNOperationQueue, and add my NSOperation to the queue.

Answer 1

Update: Fixed. I had neglected to create an SNOperationQueue, and add my NSOperation to the queue.