Break while loop app designer

I need to break out of an infinite while loop using a toggle switch. That is, when the switch is set to on , the while loop will execute until the switch is set to off , please assist ,I have little experience with app designer . Thanks in advance.

Answer 1

[Benjamin Kraus]

Consider this example (you should be able to use this same pattern within App Designer with only a little tweaking):

function spinner

f = uifigure;
b = uibutton(f,'Text','Stop');
ax = uiaxes(f);
t = linspace(0,2*pi,100);
p = plot(ax,cos(t),sin(t),'Marker','.','MarkerSize',12,'MarkerIndices',1);

% For this example I'm using a "global" variable, but for your real app you
% will want to add a property to your app.
keepRunning = true;

% Move the button above the axes.
b.Position(2) = sum(ax.Position([2 4]));
b.ButtonPushedFcn = @(~,~) stopButtonPushed();

% Start the while loop
while keepRunning
    p.MarkerIndices = mod(p.MarkerIndices,100)+1;
    
    % It is essential you put either a drawnow or a pause in your while
    % loop, otherwise your stopButtonPushed will never run.
    drawnow
end

function stopButtonPushed()
    keepRunning = false;
end

end

A more advance approach uses a timer instead of a while loop:

function spinner

f = uifigure;
s = uiswitch(f);
ax = uiaxes(f);
t = linspace(0,2*pi,100);
p = plot(ax,cos(t),sin(t),'Marker','.','MarkerSize',12,'MarkerIndices',1);

% Move the switch above the axes.
s.Position(2) = sum(ax.Position([2 4]));

% Use a timer to run your code instead of a while loop.
t = timer('Period',0.1,'ExecutionMode','fixedRate','TimerFcn',@(~,~) loop(p));

% Make sure your timer is deleted when the figure closes.
f.CloseRequestFcn = @(~,~) done(f, t);

% Use the switch to start and stop the timer.
s.ValueChangedFcn = @(~,~) switchToggled(s, t);

function switchToggled(s,t)
    if s.Value == "On"
        start(t);
    else
        stop(t);
    end
end

function loop(p)
    p.MarkerIndices = mod(p.MarkerIndices,100)+1;
    drawnow
end

function done(f, t)
    % You need to delete timers, or they will live until you close MATLAB.
    stop(t);
    delete(t);
    delete(f);
end

end