How to connect an unlocked iphone to my carrier?

I have Boost Mobile, and currently have an Android.

If I was to buy an unlocked iphone, how would I go about connecting it to Boost Mobile?

Is Boost Mobile even compatible with an iphone?
Would I have to buy a certain type of iphone to ensure that it connects to my network?

By the way, Boost Mobile is a prepaid monthly phone service and runs off Sprint network towers. I'm not sure if this helps answers the question.

I just don't want to put down a lot of money for a phone that might not even work with my network/carrier.