Case B

test.swift

class CellNode: ASCellNode {

  let contentNode = ASDisplayNode()
  
  
  override init() {
     super.init()
     self.ASM = true
     
     self.contentNode.ASM = true
     self.contentNode.layoutSpecBlock = { [unowned self] _ -> ASLayoutSpec in 
        return self.contentLayoutSpec()
     } 
  }

  override func layoutSpecThatFits() -> ASLayoutSpec {
     return ASInsetLayoutSpec(insets: .zero, child: contentNode)
  }
  
  func contentLayoutSpec() -> ASLayoutSpec {
      return ASLayoutSpec()
  }

}