Keys not registering on the iPhone while typing fast, does it happen to you or just me? I've tried this on all major OS versions of the iPhone, and on an iPhone 3G and 4. It's been around for at least a year.

I've noticed that when I'm typing really fast (over 70 wpm) on a portrait keyboard, sometimes a key will not register as being touched. I think what's happening behind the scenes is that the fingers are moving so fast that it thinks that it's the same finger that moved from one side of the keyboard to the other in a dragging motion. (Normally when you drag a key, it won't send the first key you were on and will only send the last key you released on.)

This only happens when you are typing a word where the letters alternate between the left and right fingers such that both are touching the screen at the same time. One word that it happens on is the word with where the t does not get registered and you end up with wih.

Here's how it's supposed to work:


You press your left thumb down on the t, the popup appears showing that you're going to send a t, a click sound plays. Note: the finger hasn't released the t yet, and the t hasn't been sent yet.
You press your right thumb down on the h, the t is sent, the popup appears showing that you're going to send an h, the click sound plays.
If you move your left thumb, around the keyboard, nothing happens since it's considered a dead touch (my terminology). You must release this finger before it will register again. When it is released, nothing happens. Again, this is correct behavior.
When you release your right thumb on the h, the h is sent.


What I believe it is registering when the bug happens is the following:


It detects a tap down on the t, plays a sound, shows the t popup, but doesn't send it yet.
It detects that the finger has moved to the h, and shows the h popup.
It detects that your finger was released, and it sends the h key.


Notice how in the second scenario the t key was never sent and that it thinks that it's one finger rather than two. Notice, also, that in the first scenario you hear two click sounds and in the second, you only hear one. This is actually the way I know when the bug happens, by listening for missed click sounds.

Although the example I gave with the word with may seem like it's much more likely since the t and h keys are very close by, this is actually not the case, and it frequently happens even with letters that are on opposite sides of the keyboard, such as n and d.

Note that it never happens when I type slow, since I believe touches are processed much more accurately when they aren't being sent fast. This bug doesn't happen too often (e.g. 1-5% of the time), but it's still annoying.

I'm wondering if this is a known bug or not. Has anyone else noticed this behavior? Before reporting it to Apple, it would help if I knew if other people have this issue too.
I don't know that I would classify this as a bug.  In OS X, Apple has the Key Repeat Rate setting in the Keyboard preference pane which is a similar idea.  Apple currently provides no way to adjust the speed at which key press (more correctly, release) events are registered globally in iOS.

The ability to type over 70 wpm on the portrait iPhone keyboard is something most of us are unable to achieve, so it's unlikely it would be addressed by Apple.