How to use stepper to modify the value in TableView?

I use TableView to display my dictionary data

["Coffee":1,"Juice":3,"Milk":5]

Every time the dictionary saves different item and quantity

so I use Dynamic Prototypes

but If I put stepper on TableView , I would like to modify the value of the item

How should I know the number belongs which one ?

press stepper only change corresponding value

and the modified value need to save back dictionary