At first, I thought the new MacBook Pro touch bar was actively worse than a traditional keyboard for adjusting volume or brightness. After all, with keys you can turn the volume up or down with a quick tap. From what I saw of the touch bar you needed to tap the volume button, then adjust the slider that appears. A tap, followed by a tap-and-move motion.
I was wrong. There are a couple of gestures that let you adjust volume or brightness in one quick motion, though they’re hard to stumble upon if you don’t know about them.
The first method: tap and hold either function in the Control Strip, then move your hand to the left or the right. The level will adjust, without you ever lifting your finger.
It’s a little weird at first, because your finger isn’t on the dial that’s being adjusted. But once you get used to this, it will become second nature.
The second faster method, available as of macOS High Sierra, is to quickly swipe the button itself.
This is perfect when you want to quickly adjust by one level.
Is these methods faster than adjusting the volume or brightness with dedicated brightness keys? Some may think so, others may disagree. With the first gesture you can quickly find exactly the level you want in one motion, as opposed to pressing a button multiple times. But the tactile feel of adjusting settings was also pretty close to a perfect system. If you’re not sold on the flexibility of the touch bar, this feature isn’t going to convert you; if you do like the touch bar, this gesture makes it even better.
This functionality only works for volume or brightness, the two buttons labelled “Sliders” by Apple when you customize the buttons on your touch bar.
This makes sense, because most of the other buttons offer toggle binaries: things you can turn on and off, things you can open or close. Keyboard brightness, the only other thing I think could work as a dial, isn’t offered as a Control Strip button; you can only adjust that in the Expanded Control Strip, which works more like the keyboard buttons of old.