what is the process to make and ios shopping cart app?

The same as for any other application:
1) Consider the end product a user point of view.
2) Specify your app.
3) Design the app based on the specification.
4) Code to the design.
5) Test the code.
6) Repeat from 1, 2, 3, 4, 5 as necessary until you have a product.
7) Get it tested by real world users, and repeat from 1, 2, 3, 4, 5 as necessary until they stop finding problems and complaining.

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