- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //当应用程序第一次打开时会进到这里，可以做应用程序的数据界面等的初始化操作。
    // Override point for customization after application launch.
    return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application
{
    //当应用将要失去焦点(控制权限)时，比如电话，短信，home，退到了后台。。会进到这里
    //可以在这里做程序进入后台前的操作。例如：停掉定时器，暂停某些线程的运行。停止动作，游戏等。   
    /*
     Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
     Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
     */
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{  
    //当应用进入后台之后会进到这里来。。可以释放一些资源，保存数据，关定时器，   
    /*
     Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
     If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
     */
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
    //当应用从后台到前台时会进到这里来。。   
    /*
     Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
     */
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    //当应用每次(包括第一次)获取控制权得到交点时会进到这里来。。   
    /*
     Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
     */
}
- (void)applicationWillTerminate:(UIApplication *)application
{
    //当应用在后台没杀掉时吧？？？   
    /*
     Called when the application is about to terminate.
     Save data if appropriate.
     See also applicationDidEnterBackground:.
     */
}