Is the spacing between values uniform? If so, you can set the step property.
If not, I think you would have to have your callback function process the slider value and set it to the predetermined value that is closest.
% Assume this is the slider value
value = 2.1;
% Assume this is the list of values you want the slider to take
myVals = [1.23 2.45 3.76 4.01];
% find the closest value
[~,ind] = min(abs(myVals-value))
valAct = myVals(ind)
Once you have identified the predefind value to use, set the slider's value property to that value.
app.Slder.Value = valAct;
I wrote the code the way I did so that it will execute here. You will of course need to adapt it to work within your app.
