I've seen demo mobile apps that used the vibration motor to give haptic feedback, simulating the feel of buttons and such as you moved your finger across the screen. At the time I thought for sure the next iPhone would feature "Haptic Touch" apis and it would just be a given in a few years. Still waiting...
UIFeedbackGenerator (https://developer.apple.com/documentation/uikit/uifeedbackge...) has been around for a while, but it’s not exactly capable of "positional" feedback. Still, vibrating in response to actions such as rearranging list entries or drag interactions that require a certain distance threshold to be passed can feel quite satisfying.
Well there is haptic feedback on the newer phones, usually to tell you you've crossed some drag- or timer-based threshold, but yeah it's pretty limited in scope.
