title: libz.dylib versus libz.1.2.3.dylib versus libz.1.2.5.dylib
body: <p>I asked this in a comment but this seems like an issue that deserves its own question.</p>
  
  <p>I have a project that's shared between three different installations of XCode and two different installations of the iOS SDK.  At the moment unifying the developers involved is not an option.</p>
  
  <p>When I installed the iOS 5 Beta and XCode 4.2 <code>libz.1.2.3.dylib</code> was nowhere to be found.  I discovered that linking against <code>libz.1.2.5.dylib</code> handled this but this was not compatible with the other active installations of XCode and the iOS SDK.</p>
  
  <p>I researched this online and discovered the above suggestion and <a href="https://stackoverflow.com/questions/6779951/xcode-4-2-link-error-libz-issue">this</a> suggestion.  The former doesn't work for me, and the latter makes me nervous.</p>
  
  <p>So what's the difference between <code>libz.dylib</code>, <code>libz.1.2.3.dylib</code> and <code>libz.1.2.5.dylib</code> and can I safely link to the first across all installations of XCode and the iOS SDK?</p>