Ability to lock screen

Can you please elaborate on that? The editor only changes the zoom level, when you use a pinch-to-zoom gesture. You can also change the font size and word wrap position in settings if you want to permanently have another size.

Either of these solutions would resolve this issue for me. Thanks for the quick feedback & great information.

You're welcome :)

When I scroll through a file it "moves" or "shakes" on the screen. This is actually a common problem with iOS apps (most PDF readers have had this issue at some point). The best example I can give is to open a file, touch the screen and "scroll" left to right. The whole file moves. Now "flick" the screen up or down in a traditional iOS gesture and while you get the proper up/down scrolling the file will also drift either to the left or right (depending on your own natural tendancy to flick up-left/up-right/down-left/down-right). The "flick" is just a good way to show the problem, it happens even when you a slow careful drag up or down to scroll.

This is less about the the zoom feature it self, but rather a side-effect of having the zoom at all. The only time it is not an issue is when the file is zoomed out such that the entire width fits on the screen (when there are grey "margins" to either side).

Ah, ok, now I see what you mean.

I just had a look at the UIScrollView documentation. There is a property named "directionalLockEnabled":
"If this property is YES and the user begins dragging in one general direction (horizontally or vertically), the scroll view disables scrolling in the other direction. If the drag direction is diagonal, then scrolling will not be locked and the user can drag in any direction until the drag completes. The default value is NO"

I guess setting this to YES this would solve your issue, right? I'll test it and probably enable it for the next version.

As an alternative, this wouldn't happen when this features is implemented: http://feedback.textasticapp.com/feedback/7570-automatically-adjust-word-wrap-to-fit-screen/

The width of the text would always be less than (or equal to) the view width of the editor and so it wouldn't scroll sideways.