“It worked!
I hadn't really used my Raspberry Pi 3 until recently. When I started to use it, I noticed some fairly frequent undervoltage warnings. Some of my USB power supplies are supposed to be able to deliver a suitable current for the Pi 3, but they all gave undervoltage warnings except an Apple power supply. Since I had another use for the Apple power supply -- powering Apples :-) -- I ordered this official power supply. I am delighted to be able to report that it works perfectly ... no more undervoltage warnings. Thanks!”