I’m trying to work on a prototype for a client. We’ll be building an iOS app since our core users are mostly iPhone users. Right now I’m at the Hi-Fidelity wireframe phase, where I’ll be building an interactive prototype for the users, without any branding/ colors. Just to test the idea.

My problem is that I can’t decide which iPhone artboard to go with. I hate it when, with some prototypes, you end up having weird black bars when it’s not built for your phone’s screen ratio. Should I just go with an ‘iPhone X’ artboard or is there a way to make it more responsive where it fits all iPhone sizes?