iOS 8显示应用角标

1. iOS 8角标显示须要用户授权，可在应用启动时请求授权:

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
     {
        if ([[UIDevice currentDevice].systemVersion doubleValue] >= 8.0)
        {
            UIUserNotificationType types = UIUserNotificationTypeBadge | UIUserNotificationTypeSound | UIUserNotificationTypeAlert;
            UIUserNotificationSettings *notificationSettings = [UIUserNotificationSettings settingsForTypes:types categories:nil];
            [[UIApplication sharedApplication] registerUserNotificationSettings:notificationSettings];
        }
        else
        {
            UIRemoteNotificationType types = UIUserNotificationTypeBadge | UIUserNotificationTypeSound | UIUserNotificationTypeAlert;
            [[UIApplication sharedApplication] registerForRemoteNotificationTypes:types];
        }
    
        return YES;
    }

2. 显示角标:

- (void)showBadgeNumbers
{
　　 // Request Method(服务器返回指定数据datas)

　　 // 若无新数据
    if ([datas isEqualToString:@"0"])
    {
        [self cleanBadgeNumber];
    }
    else
    {
        // tabBarItem右上角显示未读数
        self.tabBarItem.badgeValue = datas;
        // 应用右上角显示未读数
        [UIApplication sharedApplication].applicationIconBadgeNumber = datas.intValue;
    }
}

3. 清空角标:

- (void)cleanBadgeNumber
{
    // 清空tabBarItem右上角未读数
    self.tabBarItem.badgeValue = nil;
    // 清空应用右上角未读数
    [UIApplication sharedApplication].applicationIconBadgeNumber = 0;
}

4. 设置定时器自动调用

- (void)viewDidLoad 
{
    [super viewDidLoad];
　　 // 显示未读数
    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:30 target:self selector:@selector(showBadgeNumbers) userInfo:nil repeats:YES];
    // 加入Runloop
    [[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}

5. 应用进入后台继续调用

- (void)applicationDidEnterBackground:(UIApplication *)application 
{
    // 向操作系统申请后台运行资格, 后台运行时间受系统控制
    __block UIBackgroundTaskIdentifier taskIdentifier = [application beginBackgroundTaskWithExpirationHandler:^{
        // 后台运行时间已经结束
        
        // 结束任务
        [application endBackgroundTask:taskIdentifier];
    }];
}