I understand that you trying to create and use class constructor in App Designer.
In your app, create a new class file in the same folder as your app file. Define a handle class by creating a ‘classdef’ block. Below is the sample code.
classdef YourClassName < handle
% ...
end
Now define properties and methods in your class. To access the data object from within App Designer, create an instance of the class in your App Designer code and store it in a property of your app.
You can refer to this documentation for more detailed explanation: https://www.mathworks.com/help/matlab/creating_guis/organize-app-data-in-complex-apps-using-matlab-classes.html
I hope this information helps in resolving your query.
