duplicate symbol _main in:
/Users/gavin/Library/Developer/Xcode/DerivedData/EnglishHeadline-gpiuxsetwvexoqadnljzwzgqvrwf/Build/Intermediates/EnglishHeadline.build/Debug-iphoneos/EnglishHeadline.build/Objects-normal/arm64/main-91435712FE5AEA2B.o
/Users/gavin/Library/Developer/Xcode/DerivedData/EnglishHeadline-gpiuxsetwvexoqadnljzwzgqvrwf/Build/Intermediates/EnglishHeadline.build/Debug-iphoneos/EnglishHeadline.build/Objects-normal/arm64/main-D3BB34C894BCAB32.o
duplicate symbol _main in:
/Users/gavin/Library/Developer/Xcode/DerivedData/EnglishHeadline-gpiuxsetwvexoqadnljzwzgqvrwf/Build/Intermediates/EnglishHeadline.build/Debug-iphoneos/EnglishHeadline.build/Objects-normal/arm64/main-91435712FE5AEA2B.o
/Users/gavin/Library/Developer/Xcode/DerivedData/EnglishHeadline-gpiuxsetwvexoqadnljzwzgqvrwf/Build/Intermediates/EnglishHeadline.build/Debug-iphoneos/EnglishHeadline.build/Objects-normal/arm64/main-9B397D594F78D06B.o
ld: 2 duplicate symbols for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
2 duplicate symbols for architecture arm64，看到这个首先想到的是你工程中的库是否支持64位？然后在图中所示红线出进行相应的修改
原因是main重复导入，工程里面出现了三个main，然后删掉了两个，运行成功了
关于duplicate symbol _main in的解决办法
原文：http://www.cnblogs.com/er-dai-ma-nong/p/4891752.html