Undefined symbols for architecture arm64: 错误

Undefined symbols for architecture arm64:

"OBJC_CLASS$_YYCache", referenced from:

  objc-class-ref in LFNetworking.o

"OBJC_CLASS$_AFHTTPRequestSerializer", referenced from:

  objc-class-ref in LFNetworking.o

"OBJC_CLASS$_AFJSONResponseSerializer", referenced from:

  objc-class-ref in LFNetworking.o

"OBJC_CLASS$_AFHTTPSessionManager", referenced from:

  objc-class-ref in LFNetworking.o

ld: symbol(s) not found for architecture arm64

出现这种错误有多种可能：

1.Build Setting->Architectures查看是否包含arm64指令集

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2.如果用CocoaPods导入的库，Build Setting->Linking->Other Linker Flags，添加$(inherited)

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3.该类只有@interface，没有@implementation