Touches ended

[marcussatellite]

removed unnecessary code from touchesEnded throughout entire app. whitespace. higher order swift.

[sieren]

Small observation:

for _ in touches {
  value = 1 - value 
  setValueCallback(value)
}

is there any reason we're having the Knobs react to multiple touches? In this case I'd say let's get rid of the for loop and do a guard let touch = touches.first else { return } followed by the value callback/value calc. Refering to the touchesBegan code which we could also refactor this way while we're at it.