What are the methods on SpringBoard to handle the life cycle of application?

Question

Or maybe there is some method will accept the notification of an application's life cycle notification. What is the SpringBoard equivalent of methods like application: didEnterBackground?

Answer 1

I think you're looking for -(void)frontDisplayDidChange:(id)arg1; found in the SpringBoard header. From the iPhoneDevWiki:

Whenever a different app is displayed, frontDisplayDidChange:(id *)newDisplay is called. newDisplay is a reference to the SBApplication of the displayed app if the app was switched to, or it is nil if the homescreen is now showing. However, in some situations, it may be a reference to a UIViewController. For example, when the lockscreen is shown, newDisplay references an instance of SBLockScreenViewController.

Additional related methods:

-(id)_accessibilityFrontMostApplication; // returns an SBApplication reference
-(id)_accessibilityTopDisplay; // returns an SBDisplay reference
-(id)_accessibilityRunningApplications; // returns an array of SBApplication references
-(BOOL)_accessibilityShouldAllowAppLaunch;
-(BOOL)_accessibilityShouldAllowIconLaunch;
-(BOOL)_accessibilityObjectWithinProximity;