Detecting when 'Home' is pressed or app is resumed (Keyboard is covering View when it resumes)

In my iPhone app, if the user presses the Home button while the keyboard is up, then returns to the app, the keyboard is still up but my view behind is hidden behind it!

I have some code that normally would rise and lower the view as necessary, but I can't see开发者_开发百科 how to call it in this situation. How can I either detect when Home has been pressed so I can lower the keyboard, or detect when the app has been resumed so that I can rise my view?

Your application delegate is sent the applicationDidEnterBackground: message:

You should perform any tasks relating to adjusting your user interface before this method exits

you can check with some notification and try this