[pi18n]

You don't even need a jailbroken phone, just a provisioning profile. Objective-C is fully dynamic, so you can override UIView/CALayer so that it sends data to a server whenever it changes and is a child view of the key UIWindow.

They don't say it explicitly, but I would be shocked if Reveal does not work the same when testing on a device.

[DHowett]

You would still need a way to get your code running in another process; simply replacing the implementations of methods in your own application would not cause them to change system-wide.

[pi18n]

You are right, of course. I thought the GP just wanted it for his own apps.