Apple's iPhone 15 Pro was initially planned to feature haptic volume and power buttons as part of Project Bongo, a redesign of the buttons using haptic technology. The haptic buttons would detect pressure and create vibrations to emulate the sensation of pressing a physical button. However, the project was canceled due to unsatisfactory test results and high hardware failure rates. The final mass production units of the iPhone 15 Pro feature standard mechanical buttons instead. Apple may be working on a replacement for the haptic buttons for the iPhone 16 lineup, potentially incorporating capacitive buttons.
Apple has nixed the plan to introduce solid-state haptic volume buttons in the upcoming iPhone 15 Pro models, and will instead introduce them next year in the iPhone 16 Pro models. The delay is due to unresolved technical issues and the costs and complexity of the feature. The more affordable iPhone 16 models will retain the same volume button design as the iPhone 14 and the upcoming iPhone 15. The iPhone 15 Pro models will use the standard two button look for volume, but will adopt a mute button instead of a mute switch.
Apple has cancelled the plan to replace physical power and volume buttons with haptic ones in the upcoming iPhone 15 Pro, but the rumored Action Button will still be included. The Action Button will replace the mute switch and can be programmed to perform various functions such as launching Siri or the camera. The cancellation of the haptic buttons is a big deal at this stage of the design process, but it should not delay the phone's production. Apple is currently in the EVT phase of production, where unexpected changes are not typically made.
