有时候用别人的框架，你会碰到下面的错误，很是吓人，什么玩意，我怎么看不懂！！！
Undefined symbols for architecture i386:
"_RELEASE", referenced from:
-[DemoAnnotationView dealloc] in DemoAnnotationView.o
"_crc32", referenced from:
-[ZipArchive addFileToZip:newname:] in ZipArchive.o
_unzReadCurrentFile in unzip.o
_zipWriteInFileInZip in zip.o
"_deflate", referenced from:
_zipWriteInFileInZip in zip.o
_zipCloseFileInZipRaw in zip.o
"_deflateEnd", referenced from:
_zipCloseFileInZipRaw in zip.o
"_deflateInit2_", referenced from:
_zipOpenNewFileInZip3 in zip.o
"_get_crc_table", referenced from:
_unzOpenCurrentFile3 in unzip.o
_zipOpenNewFileInZip3 in zip.o
"_iconv", referenced from:
_qr_code_data_list_extract_text in libzbar.a(qrdectxt.o)
"_iconv_close", referenced from:
_qr_code_data_list_extract_text in libzbar.a(qrdectxt.o)
"_iconv_open", referenced from:
_qr_code_data_list_extract_text in libzbar.a(qrdectxt.o)
"_inflate", referenced from:
_unzReadCurrentFile in unzip.o
"_inflateEnd", referenced from:
_unzCloseCurrentFile in unzip.o
"_inflateInit2_", referenced from:
_unzOpenCurrentFile3 in unzip.o
......
IOS编译时有时出现这样的错误，要注意，错误不在Undefined for architecture i386，而是下面下划线开头的变量没定义，此时需要导入libz到项目即可。
Build Phases ——> Link Binary With Libraries 中导入libz.1.2.5.dylib即可。
提醒：下次如果再碰到crc链接错误，请把libz.dylib加入到项目中去。