iOS APP 的生命周期

1.在手机桌面上点击APP图标

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

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

- (void)viewDidLoad

- (void)viewWillAppear:(BOOL)animated

- (void)viewWillLayoutSubviews

- (void)viewDidLayoutSubviews

- (void)applicationDidBecomeActive:(UIApplication *)application

- (void)viewDidAppear:(BOOL)animated

2.通过按Home键使应用程序切入到后台

- (void)applicationWillResignActive:(UIApplication *)application

- (void)applicationDidEnterBackground:(UIApplication *)application

3.再次进入APP

- (void)applicationWillEnterForeground:(UIApplication *)application

- (void)applicationDidBecomeActive:(UIApplication *)application

4.再次按Home键，然后直接kill掉这个程序

- (void)applicationWillResignActive:(UIApplication *)application

- (void)applicationDidEnterBackground:(UIApplication *)application