UIApplication, UIApplicationDelegate 호출 순서

프로그램 최초 실행시

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
- (void)applicationDidBecomeActive:(UIApplication *)application

프로그램 백그라운드모드로 전환시 (멀티태스킹 지원되는 iOS)

- (void)applicationWillResignActive:(UIApplication*)application
- (void)applicationDidEnterBackground:(UIApplication *)application

프로그램 포그라운드모드로 전환시

- (void)applicationWillEnterForeground:(UIApplication *)application
- (void)applicationDidBecomeActive:(UIApplication *)application

프로그램 완전 종료시 (멀티태스킹 지원되지 않는 iOS)

- (void)applicationWillResignActive:(UIApplication*)application
- (void)applicationWillTerminate:(UIApplication*)application

화면잠갔다가 풀기
- (void)applicationWillResignActive:(UIApplication*)application
- (void)applicationDidBecomeActive:(UIApplication *)application

홈버튼 더블탭 동작시
- (void)applicationWillResignActive:(UIApplication*)application
- (void)applicationDidBecomeActive:(UIApplication *)application

백그라운드모드로 전환 후 다시 실행시킬 때
- (void)applicationWillResignActive:(UIApplication*)application
- (void)applicationDidEnterBackground:(UIApplication *)application
- (void)applicationWillEnterForeground:(UIApplication *)application
- (void)applicationDidBecomeActive:(UIApplication *)application

** 정리
프로그램 실행된 상태에서 슬립모드로 전환했다가 화면잠금을 푸는 경우와 홈버튼 더블탭 동작시 루틴이 동일하여 두 동작 차이를 구분할 수가 없다.