Problem with Matlab gui quitting

So i want to create a gui which is basically a timer which counts down from 30 minutes.

Which is something like above. Whenever i click the "Run" button to execute the GUI, the timer will display and countdown.

The code i used is:

function countdown(app)
            while true
                minute = 29;
                set(app.ParallelPoolidletimerTextArea, 'Value', num2str(minute));
                seconds = 0;
                set(app.TextArea, 'Value', num2str(seconds));
                while minute > 0
                    seconds = 59;
                    while seconds > 0
                        set(app.TextArea, 'Value', num2str(seconds));
                        pause(1);
                        seconds = seconds - 1;
                    end
                    minute = minute - 1;
                    set(app.ParallelPoolidletimerTextArea, 'Value', num2str(minute));
                end
            end
        end

Since the GUI has a startup function, i just did:

        function startupFcn(app)
            app.countdown;
        end

Hence the countdown works, but the problem is when i quit the application, Matlab throws me an error saying:

        Invalid or deleted object.
        Error in app.countdown.
        Error in runStartupFcn(app, @startupFcn)

Why is this happening?

Answer 1

[Ajay Kumar]

Try this:

write countdown(app) instead of app.countdown in startupFcn.