swift 控制转移 switch fallthrough while退出循环 标记
swift 中的switch语句 去掉了break语法但是如果遇到了需要case穿透的地方可以添加此关键字 fallthroughcode//: A UIKit based Playground for presenting user interfaceimport UIKitlet somePoint=(2,-2)switch somePoint { case let(x,y) where x==y : print("(\(x),\(y))is on
