Undefined symbols for architecture x86_64: "_main", referenced from: implicit entry/start for main executable ld: symbol(s) not found for architecture x86_64 clang: error: linker command faile

解决办法：Swift : 在Build Phases 中的compile sources中添加APPDelegate.swift文件

　　　　　Objective-C :在Build Phases 中的compile sources中添加main.m文件