Get data from appdesigner GUI application in another class

I have a series of classes I'm building to maintain a data hierarchy. I want to be able to use a collection of GUIs in order to collect user input and allow the user to execute certain member functions of the classes.

The particular issue I am having is that I, upon hitting a "confirm" button on a GUI, want to have some of the data from that GUI available in the class that I am calling it from, while also closing the window.

An example of my current code is below. This will appear in the constructor of the top-level class, as the GUI is used to collect data that is needed to create a new top-level object.

% Instantiate GUI
hGUI = MyGUIClass;  % Stays open until user hits "confirm" button; want to get data from the GUI in THIS class upon confirm
waitfor(hGUI);

How can I go about getting data out of my GUI in a separate class while also holding execution until the window is closed?