How do you use the item exchange?

The new commercial hub trade update means that instead of buying resources for money you can now only trade resources for other resources and items. You can do this at anytime though and don't need to call in a helicopter to do it. You can still sell resources but need a helicopter to be present to do this.

To make a trade just tap on the item you want, the cost in resources is shown, and then tap on the button with the resources you are spending. If you don't have the resources available then you can tap at the top to open the resources from stores crates (if you have them). All trades are optional, but if you have a lot of one resource and are in need of another then you can swap them here. There are new trades reset each day.