Deploying cocoa application and its C++ dylib how to pack them?

Question

I am new to cocoa and mac development. I have written an application which is combination of objective-c using cocoa framework and backend written in C++ library dylib.

I am using xcode 4.6 and have the above two projects Cocoa app and my C++ library. C++ is also my own project.

Now it is time for deployment. I want to make a pkg installer for it. I could run/debug it in the xcode 4.6 because I had added search library path in the object-c project settings to be the output directory of the C++ project. Therefore it could find the dependency and run without crash.

Now in the Objective-C project tree inside the xcode I see products -> mysoftware.app file. if I find the location of this mysoftware.app file in the finder and run it, it crashes. I open the package contents of this app files and I see contentsfollowing structure

   contents\(info.plist, MacOS, pkginfo, resources )

I do not see my C++ library in there, when I run mysoftware.app directly double clicking it crashes as it can not find the dylib I see the stack trace in the report window it can not find dylib, complaning that library not found usr/local/lib/mylib.dylib I have also manually put the dylib file in the .app within the MacOS where my executable is, hoping that it will find the lib from the same directory, it did not , gave the same message above and looking from the the sane location /usr/local/lib/mylib.dylib

So my question is how do I resolve dependency of .app package for deployment, should I need to put the dylib inside the .app package ? how do I do that and then my next step would be to put this single .app thing in the pkg installer,

Thanks

Answer 1

This is what worked for me:

1. Drag the dylib into your Frameworks.
2. Add a Copy Files build phase, destination Frameworks and put the dylib there.
3. Add a Run Script phase which has the following script:

MYLIBNAME=libmylib.dylib
install_name_tool -change /usr/local/lib/$MYLIBNAME @executable_path/../Frameworks/$MYLIBNAME  "$BUILT_PRODUCTS_DIR/$EXECUTABLE_PATH"

That's it. The script tells your app to load the dylib from the right place - otherwise it will complain about not finding the dylib at runtime.

Note that you don't need to change anything in the dylib itself - it could be supplied from elsewhere.

Answer 2

I resolved it so I am putting up this answer to help others who want to do the same. The dylib has to go in one of the sub folders within the application bundle (i.e. mysoftware.app). Could be MacOS, Frameworks or any sub folder we decide to put it in.

The first step is in the target settings of our dylib, we set the install path to be relative to the app bundle (mysoftware.app), so in Xcode target settings of lib I set it to:

@executable_path/../frameworks  

You can also use @rpath (You might want to research on that, I think it is more flexible than @executable_path)

Xcode will change the install name as well for our dylib.

Then in the Objective-C project using our dylib in the Project settings -> Build phases -> Link -> we drag our dylib here from the products node of the dylib project.

In the Objective-C/Cocoa project, the last step is to add a build step named copy files, and it should show a combo box telling you the target folder of the bundle. I set it to frameworks (this will depend on that relative path you choose when setting install path of your dylib) . The second part of the 'Copy Files' build step is to provide the souce file to copy. That's our dylib file that we want to pack in the bundle's Frameworks folder. So drag the dylib file from the products (of your dylib project) to the source file of the build step.

And that's it.

Now when we build the Objective-C or Cocoa project, if our build steps and install_path , etc are correctly configured, it should build fine. After a successfull build of the Cocoa project, go to Products -> mysoftware.app -> Locate in the Finder and when you run it, it should run fine. Since the dependency dylib is in the Frameworks folder of the bundle and correctly linked. You can see the package contents of the bundle to see if the Frameworks folder contains your dylib file.

To my surprise, the path where a dylib is stored has to be part of the dylib. So when a project links to this dylib it will copy the same path in itself, so when we run the Cocoa app which was linked to that dylib, it will look for it at exactly the same path which it copied from inside the dylib and we are responsible for telling the dylib where it exists. In the form of install_path, etc.

There are tools to manually update the dylib's install path stored in the Cocoa project using that dylib. If update the path of an existing bundle using these tools it should be changed in the client of the dylib, not required in the dylib itself.

If we've the code then we can change it in Xcode as instructed above.

otool -L my.dylib for example can be used to see the dylib install path of an existing binary lib

install_name_tool -change can be used to update the install path of existing binary lib