The problem with the iPhone is that the current design isn’t suited to wireless charging. Apple makes use of a metal rear cover, and metal and wireless charging just don’t go well together (although there are budding technologies that allow wireless charging through metal, none are yet ready for prime time). In order to add wireless charging to a smartphone or tablet, the back of the device needs to be plastic, ceramic, or glass.
Well, it just so happens that the current crop of iPhone rumors all point to Apple making a switch from aluminum to glass for the rear panel with the iPhone 8 (or whatever it ends up being called). The glass is likely to be no ordinary sheet of glass, but something similar to Corning’s Gorilla Glass, which will bring the robustness required for daily use.