Problem when doing massive load of events in the calendar ios

I'm trying to make a massive load of events in a calendar ios either locally or in gmail (The calendar is chosen by the user in the manner I describe in the following answer ) using objective-c .

Adding an event with the functions I have set up below works well for me, but when I have to do a massive load of for example 527 events (since I'm trying to add a student's school calendar) it does not work correctly.

When doing the massive load I insert well about 100 events more or less and then it starts to fail and the app is blocked.

The errors that it gives me are the following:

  

2016-11-17 17: 23: 35.966 [230: 11481] Calendar was not set: 1 Error   Domain = EKErrorDomain Code = 1 "No calendar has been selected."   UserInfo = {NSLocalizedDescription = None selected   calendar.}

     

2016-11-17 17: 23: 49.545 [230: 12644] Connectioninterrupted!

     

2016-11-17 17: 23: 49.568 [230: 12587] Error getting changed object IDs   since timestamp 501092601.149441 from daemon: Error   Domain = NSMachErrorDomain Code = 4097 "unknown error code"

My question is this, is there any error in my bulk upload approach or in the functions I have done? or otherwise Is there any other better way to make a Massive load of events?

Function that runs through the list of events and inserts them:

- (int) anyadirEventosCalendario: (EKCalendar *) cal {

    int num = 0;

    //se añade cada uno de los eventos
    for (int i=0; i < [calendario.eventos count]; i++) {

        NSDictionary * nextDict = [calendario.eventos objectAtIndex:i];
        Evento_DTO * evento_dto = [[Evento_DTO alloc] initWithEventos:nextDict];

        BOOL res = [self addEventCalendar: evento_dto calendar: cal];

        if(res){
            num++;
        }
    }

    return num;
}

And the function that adds the event to the calendar is the following:

-(BOOL)addEventCalendar: (Evento_DTO *) evento calendar: (EKCalendar *) cal{

    __block BOOL res = NO;

    if (!SYSTEM_VERSION_LESS_THAN(@"6.0")) {
        // iOS 6 and later

        EKEventStore *eventStore = [[EKEventStore alloc] init];

        //Obtenemos las fechas del evento
        Fecha_DTO *fechaStart = [[Fecha_DTO alloc] initWithFecha:(NSDictionary *)evento.dtStart];
        Fecha_DTO *fechaEnd = [[Fecha_DTO alloc] initWithFecha:(NSDictionary *)evento.dtEnd];

        // Formateamos las fechas a tipo NSDate
        // Fecha ini
        NSDateFormatter* df = [[NSDateFormatter alloc] init];
        [df setDateFormat:@"yyyyMMdd'T'HHmmss"];

        if (fechaStart.tzid == nil) {
            [df setTimeZone: [NSTimeZone systemTimeZone]];
        }else{
            [df setTimeZone:[NSTimeZone timeZoneWithName:fechaStart.tzid]];
        }
        NSDate* parsedDateS = [df dateFromString: fechaStart.fecha];

        // Fecha fin
        NSDateFormatter* df2 = [[NSDateFormatter alloc] init];
        [df2 setDateFormat:@"yyyyMMdd'T'HHmmss"];

        if (fechaEnd.tzid == nil) {
            [df2 setTimeZone: [NSTimeZone systemTimeZone]];
        }else{
            [df2 setTimeZone:[NSTimeZone timeZoneWithName:fechaEnd.tzid]];
        }
        NSDate* parsedDateE = [df2 dateFromString: fechaEnd.fecha];

        //Obtenemos las rRules
        NSString *rfc2445String = evento.rRule; // Usando la libreria EKRecurrenceRule+RRULE.m
        EKRecurrenceRule *recurrenceRule;
        if (![rfc2445String isEqualToString:@""]) {
            recurrenceRule = [[EKRecurrenceRule alloc] initWithString:rfc2445String andTimezone:fechaStart.tzid];
           // NSLog(@"RRule: %@", recurrenceRule);
        }

        if(parsedDateS!=nil){

            [eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) {

                if (granted) {
                    EKEvent *event  = [EKEvent eventWithEventStore:eventStore];
                    event.title     = evento.summary;
                    event.notes     = evento.description;
                    event.startDate = parsedDateS;
                    event.endDate  = parsedDateE;
                    event.location = evento.location;

                    if (![rfc2445String isEqualToString:@""]) // sólo añadirmos rRule si hay
                     event.recurrenceRules = [NSArray arrayWithObject:recurrenceRule];


                    event.calendar = [eventStore calendarWithIdentifier: cal.calendarIdentifier];

                    //[event setCalendar:[eventStore defaultCalendarForNewEvents]];
                    NSError *err = nil;

                    BOOL success = [eventStore saveEvent:event span:EKSpanThisEvent commit:YES error:&err];

                    if(!success){
                        if (err) {
                            NSLog(@"Calendar was not set: %li %@", (long)err.code, err.description);
                        }
                    }else{

                        //NSLog(@"EVENTO AÑADIDO");
                        res = YES;
                    }

                } else {
                    // code here for when the user does NOT allow your app to access the calendar
                    alerta = [[UIAlertView alloc]initWithTitle:AMLocalizedString(@"Error", @"")
                                                       message:AMLocalizedString(@"errorPermisosCal", @"")
                                                      delegate:self
                                             cancelButtonTitle:@"OK"
                                             otherButtonTitles:nil, nil];
                    [alerta show];
                }
            }];
        }else{
            NSLog(@"la fecha de inicio es nula");
        }

        df = nil;
        df2 = nil;
    }else{

        alerta = [[UIAlertView alloc]initWithTitle:AMLocalizedString(@"Error", @"")
                                           message:AMLocalizedString(@"VersionEvento", @"")
                                          delegate:self
                                 cancelButtonTitle:@"OK"
                                 otherButtonTitles:nil, nil];
        [alerta show];
    }
    return res;
}