Can I make a counter in App Designer?

Hi, I'm trying to make an app using App Designer that shows different phases of processing on a signal. The user will be able to configure radio button selections and drop down values such that a specific signal will be chosen when the user clicks the Run button.

The idea is that after the user configures for a specific signal and hits the Run button, the signal is shown before it is processed. Then I wish to use (arrows or) a Back button and a Forward button to show how the signal transforms during processing for fixed increments of time.

The way I hoped to accomplish this is by using a counter variable, Cnt, to increment or decrement based on if the Back or Forward button is clicked respectively.

This is a test app I've been trying. It shows either a vertical line or horizontal line based on if A or B is chosen respectively, and the Run button is clicked. The Back and Forward Button respectively decreases or increases the number of lines horizontally or vertically based on if it is A or B chosen.

This is my callback code for the Run Button:

            Ch = app.Choices.SelectedObject;
            app.UIAxes.XAxis.Limits = [0 100];
            app.UIAxes.YAxis.Limits = [0 100];

            switch Ch
                case app.Achoice

                    a = [10 10 10 10 10];
                    b = [5 30 55 80 95];
                    plot(app.UIAxes,a,b)

                case app.Bchoice

                    d = [10 10 10 10 10];
                    e = [5 30 55 80 95];
                    plot(app.UIAxes,e,d)

            end

For the Forward button callback:

            Ch = app.Choices.SelectedObject;
            app.UIAxes.XAxis.Limits = [0 100];
            app.UIAxes.YAxis.Limits = [0 100];
            app.cnt = app.cnt + 1;

            if Ch == app.AChoice
                if app.cnt == 1

                    a = [10 10 10 10 10];
                    b = [5 30 55 80 95];
                    plot(app.UIAxes,a,b)
                    hold on
                    a1 = [30 30 30 30 30];
                    plot(app.UIAxes,a1,b)

                elseif app.cnt == 2

                    a = [10 10 10 10 10];
                    b = [5 30 55 80 95];
                    plot(app.UIAxes,a,b)
                    hold on
                    a1 = [30 30 30 30 30];
                    plot(app.UIAxes,a1,b)
                    hold on
                    a2 = [50 50 50 50 50];
                    plot(app.UIAxes,a2,b)

                elseif app.cnt == 3

                    a = [10 10 10 10 10];
                    b = [5 30 55 80 95];
                    plot(app.UIAxes,a,b)
                    hold on
                    a1 = [30 30 30 30 30];
                    plot(app.UIAxes,a1,b)
                    hold on
                    a2 = [50 50 50 50 50];
                    plot(app.UIAxes,a2,b)
                    hold on
                    a3 = [70 70 70 70 70];
                    plot(app.UIAxes,a3,b)

                elseif app.cnt == 4

                    a = [10 10 10 10 10];
                    b = [5 30 55 80 95];
                    plot(app.UIAxes,a,b)
                    hold on
                    a1 = [30 30 30 30 30];
                    plot(app.UIAxes,a1,b)
                    hold on
                    a2 = [50 50 50 50 50];
                    plot(app.UIAxes,a2,b)
                    hold on
                    a3 = [70 70 70 70 70];
                    plot(app.UIAxes,a3,b)
                    hold on
                    a4 = [90 90 90 90 90];
                    plot(app.UIAxes,a4,b)

                else
                    errordlg('','Too High')
                end

            elseif Ch == app.BChoice
                if app.cnt == 1

                    d = [10 10 10 10 10];
                    e = [5 30 55 80 95];
                    plot(app.UIAxes,e,d)
                    hold on
                    d1 = [30 30 30 30 30];
                    plot(app.UIAxes,e,d1)

                elseif app.cnt == 2

                    d = [10 10 10 10 10];
                    e = [5 30 55 80 95];
                    plot(app.UIAxes,e,d)
                    hold on
                    d1 = [30 30 30 30 30];
                    plot(app.UIAxes,e,d1)
                    hold on
                    d2 = [50 50 50 50 50];
                    plot(app.UIAxes,e,d2)

                elseif app.cnt == 3

                    d = [10 10 10 10 10];
                    e = [5 30 55 80 95];
                    plot(app.UIAxes,e,d)
                    hold on
                    d1 = [30 30 30 30 30];
                    plot(app.UIAxes,e,d1)
                    hold on
                    d2 = [50 50 50 50 50];
                    plot(app.UIAxes,e,d2)
                    hold on
                    d3 = [70 70 70 70 70];
                    plot(app.UIAxes,e,d3)

                elseif app.cnt == 4

                    d = [10 10 10 10 10];
                    e = [5 30 55 80 95];
                    plot(app.UIAxes,e,d)
                    hold on
                    d1 = [30 30 30 30 30];
                    plot(app.UIAxes,e,d1)
                    hold on
                    d2 = [50 50 50 50 50];
                    plot(app.UIAxes,e,d2)
                    hold on
                    d3 = [70 70 70 70 70];
                    plot(app.UIAxes,e,d3)
                    hold on
                    d4 = [90 90 90 90 90];
                    plot(app.UIAxes,e,d4)

                else
                    errordlg('','Too High')
                end
            else
                errordlg('','Stuff')

            end

Similar code is written for the Back button. I made the counter variable, cnt, a private property. Now the error I receive for my file, Arrow_Try.mlapp is: No appropriate method, property, or field 'AChoice' for class 'Arrow_try'.

Please help me. I have never used a counter before in App Designer.

[Raees Mohammed]

Also, I did not specify the minimum and maximum values for the cnt variable.

[Raees Mohammed]

This was the private property I made for the cnt variable:

properties (Access = private)
          cnt = 0; % Description

end

Answer 1

[Matt J]

The error message you've shown doesn't appear to be connected with 'cnt' at all. It's complaining that it doesn't recognzie "app.AChoice" . Check that app.AChoice returns what it's supposed to.

[Raees Mohammed]

Yup, you're right. I figured out that was one of the problems. It was supposed to be "app.Achoice" in my code.

I got it to work after that, so my counter works.