I'm getting the following error when trying rake a project I'm working on, and I can't figure out why. The message happens no matter what variable I sent it.

Objective-C stub for message `setTranslucent:' type `v@:c' not precompiled. Make sure you properly link with the framework or library that defines this message

Here's my app_delegate file for reference.

class AppDelegate

def application(application, didFinishLaunchingWithOptions:launchOptions)
     navigation_appearance
     @window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds)
     tableView = StopsController.alloc.init 
     @window.rootViewController = UINavigationController.alloc.initWithRootViewController(tableView)
     @window.makeKeyAndVisible
     true
end


def navigation_appearance
    UINavigationBar.appearance.setBackgroundImage UIImage.imageNamed('navbar_bg.png'),
    forBarMetrics: UIBarMetricsDefault
    UINavigationBar.appearance.setTranslucent(true)
    UINavigationBar.appearance.setShadowImage UIImage.imageNamed('navbar_shadow.png')   
end

end