NSArray *tabBarItems = self.navigationController.tabBarController.tabBar.items;
UITabBarItem *personCenterTabBarItem = [tabBarItems objectAtIndex:3];
personCenterTabBarItem.badgeValue = @"2";//显示消息条数为 2

UIImageView *dotImage = [[UIImageViewalloc] initWithImage:[UIImageimageNamed:@"red_point_small"]];
    dotImage.backgroundColor = [UIColorclearColor];
    CGRect tabFrame =self.navigationController.tabBarController.tabBar.frame;
    CGFloat x =ceilf(0.9 * tabFrame.size.width);
    CGFloat y =ceilf(0.1 * tabFrame.size.height);
    dotImage.frame =CGRectMake(x, y, 8,8);
    [self.navigationController.tabBarController.tabBaraddSubview:dotImage];

    if ([[XWGlobalHelper systemVersion] intValue] > 7.99 && [[XWGlobalHelper systemVersion] intValue] < 9.001) {
      
//IOS8 需要 设置
UIUserNotificationSettings *settings = [UIUserNotificationSettings
settingsForTypes:UIUserNotificationTypeBadge categories:nil];
      [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
    }
    [UIApplication sharedApplication].applicationIconBadgeNumber = 3;