在XCode 4项目中编译ZipArchive

Undefined symbols for architecture armv6:
  \"_zipClose\", referenced from:
      -[ZipArchive CloseZipFile2] in ZipArchive.o
  \"_zipOpenNewFileInZip3\", referenced from:
      -[ZipArchive addFileToZip:newname:] in ZipArchive.o
  \"_unzOpenCurrentFile\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
  \"_unzGetGlobalInfo\", referenced from:
      -[ZipArchive UnzipOpenFile:] in ZipArchive.o
  \"_unzReadCurrentFile\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
  \"_unzOpen\", referenced from:
      -[ZipArchive UnzipOpenFile:] in ZipArchive.o
  \"_unzCloseCurrentFile\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
  \"_zipWriteInFileInZip\", referenced from:
      -[ZipArchive addFileToZip:newname:] in ZipArchive.o
  \"_zipOpenNewFileInZip\", referenced from:
      -[ZipArchive addFileToZip:newname:] in ZipArchive.o
  \"_unzGoToFirstFile\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
  \"_unzGetCurrentFileInfo\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
  \"_zipCloseFileInZip\", referenced from:
      -[ZipArchive addFileToZip:newname:] in ZipArchive.o
  \"_unzClose\", referenced from:
      -[ZipArchive UnzipCloseFile] in ZipArchive.o
  \"_zipOpen\", referenced from:
      -[ZipArchive CreateZipFile2:] in ZipArchive.o
  \"_unzGoToNextFile\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
  \"_unzOpenCurrentFilePassword\", referenced from:
      -[ZipArchive UnzipFileTo:overWrite:] in ZipArchive.o
ld: symbol(s) not found for architecture armv6
collect2: ld returned 1 exit status