[Unexpacted ConstrainedSize Apply issue] Automatically setNeedsLayout before ASCellNode didLoad

[GeekTree0101]

ASDisplayNode+UIViewBridge.mm

ASBinder setNeedsLayout sometime called before ASCellNode loaded

- (void)layoutIfNeeded
{
  BOOL shouldApply = NO;
  BOOL loaded = NO;
  id viewOrLayer = nil;
  {
    _bridge_prologue_write;
    shouldApply = ASDisplayNodeShouldApplyBridgedWriteToView(self);
    loaded = __loaded(self);
    viewOrLayer = _view ?: _layer;
    if (shouldApply == NO && loaded) {
      // The node is loaded but we're not on main.
      // We will call layoutIfNeeded on the view or layer when we apply the pending state. __layout will in turn be called on us (see -[_ASDisplayLayer layoutSublayers]).
      // We need to call it on main if the node is loaded to support automatic subnode management.
      // We can't release the lock before applying to pending state, or it may be flushed before it can be applied.
      [ASDisplayNodeGetPendingState(self) layoutIfNeeded];
    }
  }
  
  if (shouldApply) {
    // The node is loaded and we're on main.
    // Message the view or layer which in turn will call __layout on us (see -[_ASDisplayLayer layoutSublayers]).
    [viewOrLayer layoutIfNeeded];
  } else if (loaded == NO) {
    // The node is not loaded and we're not on main.
    [self __layout];
  }
}

In this case, ASCellNode constrainedSize can't change no more

[GeekTree0101]

Will support this code

extension Reactive where Base: ASDisplayNode {
    
    var didLoad: ControlEvent<Void> {
        let source = self.methodInvoked(#selector(Base.didLoad)).map { _ in return }
        return ControlEvent(events: source)
    }
}

extension Observable {
    func onDidLoad(_ node: ASDisplayNode) -> Observable<Element> {
        return self.withLatestFrom(node.rx.didLoad) { ($0, $1) }
            .map { $0.0 }
            .asObservable()
    }
}