For the iPad/iPhone can I detect when the user has the keypad lock turned on for inactivity?

For the iPad/iPhone can I detect when the user has the keypad lock turned on for inactivity protection?

If you have sensitive information in an application you will still often cache username/password and it is too disruptive to ask for a full username/password challenge after each period of inactivity.

I want to ensure that if the user has logged in with the username and password (and I cache it for them for convenience), the next time the device is picked up they have to type in their 4 digit pas开发者_如何学Pythonscode to unlock the device.

I'd want to be able to detect if the passcode lock setting is turned off, if it is I could build my own passcode unlocker or require a full username/password/security token authorization after every period of inactivity.

I don't think it's possible to do this on a device. See the answers to these questions for more information:

Can I tell if the iPhone has a passcode?

How can I find out if the iPhone user currently has a passcode set and encryption enabled?