float version = [[[UIDevice currentDevice] systemVersion] floatValue];

    if (version >=8.0) {

        UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];

        UIApplication *application = [UIApplication sharedApplication];

        [application registerUserNotificationSettings:settings];

        application.applicationIconBadgeNumber = 999;

    }

在设置消息推送前最好进行版本判断

例如：

    float version = [[[UIDevice currentDevice] systemVersion] floatValue];   

    if (version >= 8.0) {

        UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];

        UIApplication *application = [UIApplication sharedApplication];

        [application registerUserNotificationSettings:settings];

        [application registerForRemoteNotifications];

    }