I would find useful, in some cases, and under the user's permission, to block the device so only the running application can be accessed unless the usrer's password (pattern or whatever is used to unlock the session) is introduced.
I guess the mecanism should be something like: The application asks the os to do this, the OS asks the user for permission and then the application asks the device to block the application on "exit" or standby (or both).
This would be useful for using an iPhone or iPad as a device for public use. One example could be a Library where visitors can see the book list and some previews in the device. In this case, you don't want the user to access any other resource/application in the system.
Does it make sense?
What your asking is there any type of kiosk mode for iOS devices.
The short answer in no. The longer answer is if you're using a Jail broken device you might be able to relaunch the app on exit, but it would take significant R&D.
I hade a client ask about this last week, after some investigation and thinking I told her,
It's best to look for a case that blocks the home button. Or some kind of security bracket. It'll be cheaper and easier.
Also any App you create with this functionality would be rejected form the App store.
If your looking for advice on programming Jail broken devices there is a Stack Exchange proposal you can follow.
Supposedly there's a way to have a "kiosk" mode with a .mobileconfig file. Both of these articles talk about it, basically covering the same territory:
http://joris.kluivers.nl/blog/2012/03/02/kiosk-mode-for-ios/
http://rick-hawkins.blogspot.ca/2012/01/turning-ipad-into-kiosk-device.html
I was looking into this again and found out that iOS already supports the feature. It is called Guided Access, it was incorporated on iOS 6, it does not require jailbreak and can be used for any app installed on the device.
It makes sense, but I don't think you can do that without jailbreaking the phone. In iOS, the home button cannot be overridden by applications. Besides there is cheaper hardware out there for kiosk-style applications.
来源：https://stackoverflow.com/questions/3724968/ios-apple-is-there-any-way-for-the-application-to-ask-the-os-to-block-the-dev