title: ARC error when deploying to 10.6
body: <p>I have my app running and tested on 10.7 but later realized that I needed it to work on earlier versions as well. And unfortunately, I started this project with ARC on from the very beginning. </p>
  
  <p>Now my build setup is debug base sdk: 10.7, and release base sdk: 10.6. And when I try to archive my app, I got the following error:</p>
  
  <pre><code>Undefined symbols for architecture x86_64:
  "_objc_retain", referenced from:
    +[__ARCLite__ load] in libarclite_macosx.a(arclite.o)
    -[AppDelegate applicationDidFinishLaunching:] in AppDelegate.o
    -[AppDelegate managedObjectModel] in AppDelegate.o
    -[AppDelegate persistentStoreCoordinator] in AppDelegate.o
    -[AppDelegate managedObjectContext] in AppDelegate.o
    -[AppDelegate windowWillReturnUndoManager:] in AppDelegate.o
    -[AppDelegate saveAction:] in AppDelegate.o
    ...
   (maybe you meant: _objc_retainedObject)
  "_objc_release", referenced from:
    -[AppDelegate applicationDidFinishLaunching:] in AppDelegate.o
    -[AppDelegate applicationFilesDirectory] in AppDelegate.o
    -[AppDelegate managedObjectModel] in AppDelegate.o
    -[AppDelegate persistentStoreCoordinator] in AppDelegate.o
    -[AppDelegate managedObjectContext] in AppDelegate.o
    -[AppDelegate windowWillReturnUndoManager:] in AppDelegate.o
    -[AppDelegate saveAction:] in AppDelegate.o
    ...
  "_objc_retainAutoreleasedReturnValue", referenced from:
    -[AppDelegate applicationFilesDirectory] in AppDelegate.o
    -[AppDelegate managedObjectModel] in AppDelegate.o
    -[AppDelegate persistentStoreCoordinator] in AppDelegate.o
    -[AppDelegate managedObjectContext] in AppDelegate.o
    -[AppDelegate windowWillReturnUndoManager:] in AppDelegate.o
    -[AppDelegate saveAction:] in AppDelegate.o
    -[AppDelegate applicationShouldTerminate:] in AppDelegate.o
    ...
  "_objc_autoreleaseReturnValue", referenced from:
    -[AppDelegate applicationFilesDirectory] in AppDelegate.o
    -[AppDelegate managedObjectModel] in AppDelegate.o
    -[AppDelegate persistentStoreCoordinator] in AppDelegate.o
    -[AppDelegate managedObjectContext] in AppDelegate.o
    -[AppDelegate windowWillReturnUndoManager:] in AppDelegate.o
    -[MainWindowController viewForTag:] in MainWindowController.o
    -[MainWindowController tableView:objectValueForTableColumn:row:] in MainWindowController.o
    ...
  "_objc_storeStrong", referenced from:
    -[AppDelegate persistentStoreCoordinator] in AppDelegate.o
    -[AppDelegate saveAction:] in AppDelegate.o
    -[AppDelegate applicationShouldTerminate:] in AppDelegate.o
    -[AppDelegate .cxx_destruct] in AppDelegate.o
    -[MainWindowController init] in MainWindowController.o
    -[MainWindowController viewForTag:] in MainWindowController.o
    -[MainWindowController showUserFinderView:] in MainWindowController.o
    ...
  "_objc_retainAutoreleaseReturnValue", referenced from:
    +[MainWindowController sharedInstance] in MainWindowController.o
    -[FileMetaData getFileName] in FileMetaData.o
    -[FileMetaData getLastHash] in FileMetaData.o
    -[FileMetaData getCreationDate] in FileMetaData.o
    -[FileMetaData getLastModified] in FileMetaData.oe
    -[FileMetaData getLocalPath] in FileMetaData.o
    ...
  "_objc_autorelease", referenced from:
    -[SBJsonParser objectWithString:error:] in SBJsonParser.o
    -[SBJsonTokeniser getStringToken:] in SBJsonTokeniser.o
    -[SBJsonTokeniser getNumberToken:] in SBJsonTokeniser.o
    -[SBJsonUTF8Stream getRetainedStringFragment:] in SBJsonUTF8Stream.o
    -[SBJsonWriter stringWithObject:error:] in SBJsonWriter.o
  "_objc_retainAutorelease", referenced from:
    -[SBJsonTokeniser getStringToken:] in SBJsonTokeniser.o
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>It looks like an issue with ARC, but I have no clue where to start on fixing this. Any suggestions? Thanks.</p>