How to make a timer keep running even if game enters background in cocos2d-x c++ game in ios

Question

I am using a timer in my cocos2d-x game (c++) ios. I am using cocos2d-x 2.2 version. My function for time is as follows in my init

this->schedule(schedule_selector(HelloWorld::UpdateTimer), 1);

I have defined the function as follows.

void HelloWorld::UpdateTimer(float dt)
{
if(seconds<=0)
{
    CCLOG("clock stopped");
    CCString *str=CCString::createWithFormat("%d",seconds);
    timer->setString(str->getCString());
    this->unschedule(schedule_selector(HelloWorld::UpdateTimer));

}
else
{
CCString *str=CCString::createWithFormat("%d",seconds);
timer->setString(str->getCString());
seconds--;
}

}

Everythings is working fine. But i have this timer to keep running even if the game enters background state. I have tried commenting the body of didEnter Background in appdelegate but not successfull. Any help will be appreciated Thanks

Answer 1

In my AppDelegate.cpp I wrote the following code in applicationDidEnterBackground function. Here I took a value of time in seconds whenever the app goes background and store it in a CCUserdefault key. And when the app comes to foreground I again took the local system time and subtracted that from the time I stored in the key. Following is my code

void AppDelegate::applicationDidEnterBackground() 
{
    time_t rawtime;
    struct tm * timeinfo;
    time (&rawtime);
    timeinfo = localtime (&rawtime);

    CCLog("year------->%04d",timeinfo->tm_year+1900);
    CCLog("month------->%02d",timeinfo->tm_mon+1);
    CCLog("day------->%02d",timeinfo->tm_mday);

    CCLog("hour------->%02d",timeinfo->tm_hour);
    CCLog("minutes------->%02d",timeinfo->tm_min);
    CCLog("seconds------->%02d",timeinfo->tm_sec);

    int time_in_seconds=(timeinfo->tm_hour*60)+(timeinfo->tm_min*60)+timeinfo->tm_sec;
    CCLOG("time in seconds is %d",time_in_seconds);
    CCUserDefault *def=CCUserDefault::sharedUserDefault();
    def->setIntegerForKey("time_from_background", time_in_seconds);

    CCDirector::sharedDirector()->stopAnimation();

// if you use SimpleAudioEngine, it must be pause
// SimpleAudioEngine::sharedEngine()->pauseBackgroundMusic();
}

void AppDelegate::applicationWillEnterForeground() 
{

    CCUserDefault *def=CCUserDefault::sharedUserDefault();
    int time1=def->getIntegerForKey("time_from_background");
    time_t rawtime;
    struct tm * timeinfo;
    time(&rawtime);
    timeinfo = localtime (&rawtime);

    CCLog("year------->%04d",timeinfo->tm_year+1900);
    CCLog("month------->%02d",timeinfo->tm_mon+1);
    CCLog("day------->%02d",timeinfo->tm_mday);

    CCLog("hour------->%02d",timeinfo->tm_hour);
    CCLog("mintus------->%02d",timeinfo->tm_min);
    CCLog("seconds------->%02d",timeinfo->tm_sec);

    int time_in_seconds=(timeinfo->tm_hour*60)+(timeinfo->tm_min*60)+timeinfo->tm_sec;
    int resume_seconds= time_in_seconds-time1;
    CCLOG("app after seconds ==  %d", resume_seconds);
    CCDirector::sharedDirector()->startAnimation();

// if you use SimpleAudioEngine, it must resume here
// SimpleAudioEngine::sharedEngine()->resumeBackgroundMusic();
}

You can see and calculate the time the app remained in background.