- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    
    NSObject *object = [[NSObject alloc] init];
    NSLog(@"Reference Count = %u", [object retainCount]);
    
    [object release];
    NSLog(@"Reference Count = %u", [object retainCount]);
    return YES;
}
// 打印结果
// 2015-01-21 10:04:05.799 MRC_Test[2985:607] Reference Count = 1
// 2015-01-21 10:04:05.800 MRC_Test[2985:607] Reference Count = 1

@property (assign, nonatomic) UIBackgroundTaskIdentifier backgroundUpdateTask;

launchOptions
{
    // Override point for customization after application launch.
    return YES;
}
							
- (void)applicationWillResignActive:(UIApplication *)application
{
    // 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
{
    
    [self beginBackgroundUpdateTask];
    
    //在这里添加需要长久运行的代码
    
    [self endBackgroundUpdateTask];
}



- (void)beginBackgroundUpdateTask
{
    self.backgroundUpdateTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        [self endBackgroundUpdateTask];
    }];
}

- (void)endBackgroundUpdateTask
{
    [[UIApplication sharedApplication] endBackgroundTask:self.backgroundUpdateTask];
    self.backgroundUpdateTask = UIBackgroundTaskInvalid;
}