Rotating wheel

local wheel = display.newGroup()
wheel.x, wheel.y = display.contentCenterX, display.contentCenterY

display.newRect(wheel, 50, 0, 10, 10)

display.newCircle(wheel, 0, 0, 5)

function wheel:touch(event)
    local x, y = self:contentToLocal(event.x, event.y)
    if event.phase == 'moved' then
        self.rotation = self.rotation + math.deg(math.atan2(y, x))
        for i= 1, self.numChildren do
            self[i].rotation = -self.rotation
        end
    end
end

Runtime:addEventListener('touch', wheel)