I have come to the realization that so far, there are only 11 iPhone chassises that are truly unique. Size variations and minor differences of the same chassis do not count, as well as the material changes such as the ones from aluminum to glass on the iPhone 8.
Unique Designs: 2G, 3G, 4, 5, 5c, 6, X, XR, 12 Pro, 17 Pro, Air
I'm counting the 12 and 12 Pro as the same design since they share most everything in common design-wise except one more camera and different metal. The 13 merely had differently oriented cameras and lower buttons. The 15 merely changed the edges and 16 again the cameras.
On an unrelated note, this is how I'd redesign the non-Pro iPhone.
Unique Designs: 2G, 3G, 4, 5, 5c, 6, X, XR, 12 Pro, 17 Pro, Air
I'm counting the 12 and 12 Pro as the same design since they share most everything in common design-wise except one more camera and different metal. The 13 merely had differently oriented cameras and lower buttons. The 15 merely changed the edges and 16 again the cameras.
On an unrelated note, this is how I'd redesign the non-Pro iPhone.