Shopping cart on iOS [closed]

I'm starting in iOS and need to make a shopping carts for my app. What I already have is a searchbar where it is possible to search the product and select it. Once this is done, it opens in another view. My idea is to have a field to add the desired amount and a buttom that adds up the value with that amount and pass to the cart. Anyway, something common in e-commerce but I do not know where to start. Thank you very much in advance. Carlos