Undefined symbols for architecture i386: “_deflate”, referenced from PlatCompress(enumCompressOperation, CompressCookie*, void*, long) in libMo.a

I also had a same error.

Add libz.dylib to framework from the target -> Build Phases tab -> Link Binaries With Libraries,

hope that will work for you.

Note: If libz.dylib not found, try adding libz.tbd