Creating a new control for the metronome slider

The built-in iPhone slider wasn’t cutting it for metronome BPM input on GuitarToolkit 1.0 through 1.1.1. In addition to being too hard to grab and inconsistent with the rest of the visual design, we got into a resolution constraint. With a 320 pixel wide screen and some padding on the ends of the slider, we were getting down to 1 pixel per BPM, which is just about impossible to fine tune with your finger.

Due to the FNDA, I can’t get into details of other constraints or how we actually implemented a solution. The end result, however, is a wheel rotated 90 and has the same inertia as other elements you may have seen on the iPhone. Give it a flick and it spins.

GTK Metronome BPM GTK Metronome BPM

This gives us unlimited pixel resolution for fine-grained control, as well as frees up some room for increment / decrement buttons to each side.