如何从它创建的对象中引用控制器？

So I have a PanelController which is a NSWindowController, and it instantiates an object called FileUploader. But inside of FileUploader, I want to be able to update some text on the Panel informing the user of the progress that has been made so far. But I don't know how to reference PanelController given that I can't instantiate a new one. So I have a PanelController which is a NSWindow