Question

I have a run loop method for a CAEAGLLayer which uses GCD for serializing access to shared ivars.

My drawing code currently is constructed like this:

- (void)draw {
    dispatch_sync(serialDrawingQueue, ^{
        @autoreleasepool {
            [self drawingStart];

            [spriteA draw];
            [spriteB draw];

            [self drawingEnd];
        }
    });
}

The draw method is called by a CADisplayLink.
Is the @autoreleasepool necessary when I use GCD blocks?

Answer 1

From the Apple docs:

If your block creates more than a few Objective-C objects, you might
want to enclose parts of your block’s code in an @autorelease block to
handle the memory management for those objects. Although GCD
dispatch queues have their own autorelease pools, they make no
guarantees as to when those pools are drained. If your application is
memory constrained, creating your own autorelease pool allows you to
free up the memory for autoreleased objects at more regular intervals.