我正在尝试刷新页脚(supplementaryElement)。我正在使用invalidatelayout方法。基于SO建议here.Apple文档here.我收到以下错误:Terminatingappduetouncaughtexception'NSInvalidArgumentException',reason:'theinvalidationcontext()sentto-[UICollectionViewFlowLayoutinvalidateLayoutWithContext:]isnotaninstanceoftypeUICollectionViewFlowLayoutIn