[ASCellNode] Retain Cycle with Backing UIViewController

[DreamingInBinary]

Texture Version - Master

If you use ASCellNode's initializer to provide a view controller block, it seems to hang on to that controller when, in my own testing, it no longer needs it. This also appears to cause a retain cycle where both the cell node and controller still hang around, even if you change your data source to new view controllers instances and reload its data.

Here's what I did to fix this:

- (void)didLoad
{
  [super didLoad];

  if (_viewControllerBlock != nil) {

    _viewController = _viewControllerBlock();
    _viewControllerBlock = nil;

    if ([_viewController isKindOfClass:[ASViewController class]]) {
      ASViewController *asViewController = (ASViewController *)_viewController;
      _viewControllerNode = asViewController.node;
      [_viewController loadViewIfNeeded];
    } else {
      // Careful to avoid retain cycle
      UIViewController *viewController = _viewController;
      _viewControllerNode = [[ASDisplayNode alloc] initWithViewBlock:^{
        return viewController.view;
      }];
    }
    [self addSubnode:_viewControllerNode];

    // Since we just loaded our node, and added _viewControllerNode as a subnode,
    // _viewControllerNode must have just loaded its view, so now is an appropriate
    // time to execute our didLoadBlock, if we were given one.
    if (_viewControllerDidLoadBlock != nil) {
      _viewControllerDidLoadBlock(self);
      _viewControllerDidLoadBlock = nil;
    }

    // ADDED: Release the controller since we've got a view controller node now
     _viewController = nil;
  }
}

Since the controller appears to only be used to setup the _viewControllerNode, nilling it out fixes the issue for me - but I'm unsure of the impact. If it sounds reasonable, I'm happy to open a PR.

[rahul-malik]

Mind putting up a PR for this?

[DreamingInBinary]

Got one right here

[rahul-malik]

Thanks for the PR, will merge soon. Did you see the retain cycle in the memory debugger? Just wanted to make sure we were making the proper fix here