swift的新手，一个人为的例子。我有一系列菜单类别，而这些菜单类别又具有菜单项我想遍历类别，然后读取项目子数组的元素。不知道将元素作为数组引用的语法第10行第18栏的错误:类型“String”不符合协议(protocol)“Sequence”对于(项目)提供{varmenuOffering=["drinks","breakfastEntree"]vardrinks:Set=["water","milk","coffee","tea","dietcoke"]varbreakfastEntree:Set=["eggs","bacon","sausage","pancakes"]for(o