使用ASIHTTPRequest的ASIDataCompressor与ASIDataDecompressor进行gzip压缩与解压缩，出现的问题

导入系统的libbz2.1.0.tbd

导入头文件#import <zlib.h>

从网上找的gzip压缩与解压缩方法

如：http://my.oschina.net/u/1244672/blog/185175

编译后，报错：

Undefined symbols for architecture x86_64:
  "_deflate", referenced from:
      +[JHEncryptTool gzipData:] in JHEncryptTool.o
  "_deflateEnd", referenced from:
      +[JHEncryptTool gzipData:] in JHEncryptTool.o
  "_deflateInit2_", referenced from:
      +[JHEncryptTool gzipData:] in JHEncryptTool.o
  "_inflate", referenced from:
      +[JHEncryptTool ungzipData:] in JHEncryptTool.o
  "_inflateEnd", referenced from:
      +[JHEncryptTool ungzipData:] in JHEncryptTool.o
  "_inflateInit2_", referenced from:
      +[JHEncryptTool ungzipData:] in JHEncryptTool.o
ld: symbol(s) not found for architecture x86_64

单独使用ASIDataCompressor与ASIDataDecompressor这两个类时，编译时，也会报同样的错！

解决办法：

Build Setting里面Other Linker Flags 添加 -lz

(2016-12-22)

另一个类似的问题：

Undefined symbols for architecture arm64:
  "_inflate", referenced from:
      +[WXOMTAHelper GUnzip:Out:] in libWeChatSDK.a(MTAHelper.o)
      -[NSData(WBSDKGZIP) wbsdk_gunzippedData] in libWeiboSDK.a(WBSDKGZIP.o)
  "_deflate", referenced from:
      +[WXOMTAHelper GZip:Out:] in libWeChatSDK.a(MTAHelper.o)
      -[NSData(WBSDKGZIP) wbsdk_gzippedDataWithCompressionLevel:] in libWeiboSDK.a(WBSDKGZIP.o)
  "_inflateEnd", referenced from:
      +[WXOMTAHelper GUnzip:Out:] in libWeChatSDK.a(MTAHelper.o)
      -[NSData(WBSDKGZIP) wbsdk_gunzippedData] in libWeiboSDK.a(WBSDKGZIP.o)
  "_deflateInit2_", referenced from:
      +[WXOMTAHelper GZip:Out:] in libWeChatSDK.a(MTAHelper.o)
      -[NSData(WBSDKGZIP) wbsdk_gzippedDataWithCompressionLevel:] in libWeiboSDK.a(WBSDKGZIP.o)
  "_inflateInit2_", referenced from:
      +[WXOMTAHelper GUnzip:Out:] in libWeChatSDK.a(MTAHelper.o)
      -[NSData(WBSDKGZIP) wbsdk_gunzippedData] in libWeiboSDK.a(WBSDKGZIP.o)
  "_deflateEnd", referenced from:
      +[WXOMTAHelper GZip:Out:] in libWeChatSDK.a(MTAHelper.o)
      -[NSData(WBSDKGZIP) wbsdk_gzippedDataWithCompressionLevel:] in libWeiboSDK.a(WBSDKGZIP.o)
ld: symbol(s) not found for architecture arm64

导入系统的libz.tbd,就解决问题了。

回头看，之前的问题，去掉

Build Setting里面Other Linker Flags 添加的 -lz

这回报错：

Undefined symbols for architecture x86_64:
  "_deflate", referenced from:
      -[ASIDataCompressor compressBytes:length:error:shouldFinish:] in ASIDataCompressor.o
  "_deflateEnd", referenced from:
      -[ASIDataCompressor closeStream] in ASIDataCompressor.o
  "_deflateInit2_", referenced from:
      -[ASIDataCompressor setupStream] in ASIDataCompressor.o
  "_inflate", referenced from:
      -[ASIDataDecompressor uncompressBytes:length:error:] in ASIDataDecompressor.o
  "_inflateEnd", referenced from:
      -[ASIDataDecompressor closeStream] in ASIDataDecompressor.o
  "_inflateInit2_", referenced from:
      -[ASIDataDecompressor setupStream] in ASIDataDecompressor.o
ld: symbol(s) not found for architecture x86_64

去掉之前导入系统库的libbz2.1.0.tbd，

换成libz.tbd,问题也解决了。

所以，libz.dylib是提供zip压缩解压缩的库。

所以，要么导入libz.tbd，要么Other Linker Flags 添加 -lz