The problem as @photoionized pointed out was partly due to the version of zlib
or libz
. Because the project was old it was using libz.1.2.3
instead of the latest libz.1.2.5
. So to update that, I found this question.
Basically I had to delete the old one and replace it with the new one.
Link against the libz.dylib, but add it through the Build Phases tab.
Project >> Target >> Build Phases >> Link Binary With Libraries
Press + under the list and select the libz.dylib then it will add the lib so it will work inbetween SDK updates.