All the notifications predefined by UIKit framework. Apple should provide this but they don't. So, take it if you need it.

UIKit_System_Notifications.h

// UIApplication.h		
UIApplicationDidEnterBackgroundNotification       __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0);
UIApplicationWillEnterForegroundNotification      __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0);
UIApplicationDidFinishLaunchingNotification;
UIApplicationDidBecomeActiveNotification;
UIApplicationWillResignActiveNotification;
UIApplicationDidReceiveMemoryWarningNotification;
UIApplicationWillTerminateNotification;
UIApplicationSignificantTimeChangeNotification;
UIApplicationWillChangeStatusBarOrientationNotification; // userInfo contains NSNumber with new orientation
UIApplicationDidChangeStatusBarOrientationNotification;  // userInfo contains NSNumber with old orientation
UIApplicationWillChangeStatusBarFrameNotification;       // userInfo contains NSValue with new frame
UIApplicationDidChangeStatusBarFrameNotification;        // userInfo contains NSValue with old frame
UIApplicationLaunchOptionsRemoteNotificationKey __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0); // userInfo contains NSDictionary with payload
UIApplicationLaunchOptionsLocalNotificationKey  __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0); // userInfo contains a UILocalNotification

// UIDevice.h		
UIDeviceOrientationDidChangeNotification;
UIDeviceBatteryStateDidChangeNotification   __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);
UIDeviceBatteryLevelDidChangeNotification   __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);
UIDeviceProximityStateDidChangeNotification __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);

// UILocalNotification.h
UILocalNotificationDefaultSoundName __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_0);

// UIMenuController.h		
UIMenuControllerWillShowMenuNotification;
UIMenuControllerDidShowMenuNotification;
UIMenuControllerWillHideMenuNotification;
UIMenuControllerDidHideMenuNotification;
UIMenuControllerMenuFrameDidChangeNotification;

// UIPasteboard.h		
UIPasteboardChangedNotification;
UIPasteboardRemovedNotification;

// UIScreen.h		
UIScreenDidConnectNotification;    // object is the UIScreen that represents the new screen. connection notifications are not sent for screens present when the application is first launched
UIScreenDidDisconnectNotification; // object is the UIScreen that represented the disconnected screen
UIScreenModeDidChangeNotification; // object is the UIScreen. [object currentMode] is the new UIScreenMode

// UITableView.h		
UITableViewSelectionDidChangeNotification;

//UITextField.h		
UITextFieldTextDidBeginEditingNotification;
UITextFieldTextDidEndEditingNotification;
UITextFieldTextDidChangeNotification;

// UITextInput.h		
UITextInputCurrentInputModeDidChangeNotification __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_4_2);

// UIWindow.h		
UIWindowDidBecomeVisibleNotification; // nil
UIWindowDidBecomeHiddenNotification;  // nil
UIWindowDidBecomeKeyNotification;     // nil
UIWindowDidResignKeyNotification;     // nil
UIKeyboardWillShowNotification;
UIKeyboardDidShowNotification; 
UIKeyboardWillHideNotification; 
UIKeyboardDidHideNotification;