Swift 3.1(7) Closures
swift能处理所有的内存管理。Swift’sclosureexpressionshaveaclean,clearstyle,withoptimizationsthatencouragebrief,clutter-freeSyntaxincommonscenarios.Theseoptimizationsinclude:InferringparameterandreturnvaluetypesfromcontextImplicitreturnsfromsingle-expressionclosuresSh