如何添加和显示新的子节点在按钮点击?

Layout Transition

- (ASLayoutSpec *)layoutSpecThatFits:(ASSizeRange)constrainedSize
{


  ASStackLayoutSpec *stack = [[ASStackLayoutSpec alloc] init];
  if (self.buttonState == SignupNodeName) {
    [stack setChildren:@[field, self.buttonNode, self.newNode]];
  } else {
    [stack setChildren:@[field, self.buttonNode]];
  }


  UIEdgeInsets insets = UIEdgeInsetsMake(15.0, 15.0, 15.0, 15.0);
  return [ASInsetLayoutSpec insetLayoutSpecWithInsets:insets child:stack];
}