Cleanest way to get iPhone controls to handlebars is Bluetooth button from Amazon. Satechi is the brand and it comes with a steering wheel mount that fits stock handgrip perfectly. 29.99. There is more than 1 type, I got the one with play/pause, volume up/down, and skip forward/back. I leave iPhone 6s in cubby plugged into aux cord and charger mounted in there. Set my genre on Amazon or Pandora and skip songs at will, pause, or volume up/down with left thumb. I don't feel the need to see phone. It really is the cleanest setup I've tried. Your phone stays out of view. Unless your phone is huge.
Jim