Bluetooth pairing (of wireless keyboards, mice, trackpads) in OS X is just a mess: unreliable, unclear, hassle-y. Thought I was going to have to switch to wired keyboard to post this gripe!
I paired my keyboard to my iPad at a coffee shop, and when I came home it was the usual pain in the arse to get it to talk to my Mac again. First the Mac can’t “find” the keyboard, even though it’s clearly on, and it won’t find it until you turn it off and on again, which is not as straightforward as you might think, because you have to HOLD the power button to turn it off, which is counter-intuitive. When the Mac finally does “find” the keyboard, then it starts failing to “pair” with it, but there are no error messages — it just doesn’t do it, and all you can do is curse and try again. As usual, I just ended up trying over and over again until eventually, on the 6th try, it worked.
I have absolutely no idea what changed. I never do.
It is not obvious whether the Apple wireless keyboard and trackpad are on or off to begin with. (The mouse has a toggle, so simply does not have this issue — it’s state is physically represented and unambiguous.)
On the keyboard, the light comes ON when you press, but then you have to hold it for a surprisingly long time before the light turns off. It is then off … but it looks the same as when it was on. When it is on, there is actually no obvious way to verify that it is on. (There is a way, but it’s non-obvious, and I forget between incidents.) And when it is off, there is also no easy way to confirm that. However, even when it is on, OS X may not “find” it — leading to the rather natural question, “Is it really on?” Which you can’t confidently confirm. And so on…
Finally, there is a substantial complication! There are two ways to turn it on! You can press once, and after a brief delay when you wonder if anything happened, the light comes on … or you can press and hold for a LONG TIME, and the power light starts flashing: which is a pairing mode. Even though it seems to be highly relevant, this is not mentioned in any way shape or form in the bluetooth connection window. Nor does it actually seem to be NECESSARY, as you CAN connect without it!
See also: Fuck Bluetooth