Undefined symbols for architecture x86_64错误原因

在Xcode7上做framework编译framework正常，但使用[XCTest]做单元测试，运行单元测试，报如下错误：

Undefined symbols for architecture x86_64:
  "_deflate", referenced from:
      +[NSData(Gzip) compress:] in EMPKit(NSData+EMPKit.o)
  "_deflateEnd", referenced from:
      +[NSData(Gzip) compress:] in EMPKit(NSData+EMPKit.o)
  "_deflateInit2_", referenced from:
      +[NSData(Gzip) compress:] in EMPKit(NSData+EMPKit.o)
  "_inflate", referenced from:
      +[NSData(Gzip) uncompress:] in EMPKit(NSData+EMPKit.o)
  "_inflateEnd", referenced from:
      +[NSData(Gzip) uncompress:] in EMPKit(NSData+EMPKit.o)
  "_inflateInit2_", referenced from:
      +[NSData(Gzip) uncompress:] in EMPKit(NSData+EMPKit.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

    开始也查到应该是其依赖类库没添加问题，但framework中也没添加，编译正常，但[XCTest]编译就是不通过，后来将target调整为单元测试对应的target，然后添加对应的依赖库，然后编译正常，具体解放方法如下：

①：找到对应的target（如：framework、test、aggregate）【这个很重要哦！】;

②：targets--->build phases----->link binary with libraries----->+选择要添加的库。

参考：

        Undefined symbols for architecture armv7:错误解决方法