This can be done one of several ways.
1. You can load one app into another app as a variable, and access its methods that way. You can see an example of loading an app into another app in this example:
https://www.mathworks.com/help/matlab/creating_guis/creating-multiwindow-apps-in-app-designer.html
2. You can share application data using the 'setappdata' and 'getappdata' functions. You can refer to the documentation for how to use these functions:
https://www.mathworks.com/help/matlab/ref/setappdata.html
3. If neither of these suffice, you can always save a method handle to the base workspace with the 'assignin' function and use it from there. You can refer to the documentation for this function here:
https://www.mathworks.com/help/matlab/ref/assignin.html
