How to get time interval for every 30:00(30 minutes) from current time to 10:30 pm

Question

Need help to show the time intervals for every 30 mins, suppose the current time is 11:45 am then

Time intervals should be : 12:00 pm,12:30 pm,01:00 pm,01:30 pm,02:00 pm,02:30 pm......10:30 pm.

 NSString *time = @"10.30 pm";

     NSDate *date1;
        NSDate *date2;
        {
            NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
            [formatter setDateFormat:@"hh.mm a"];
            date1 = [formatter dateFromString:time];
            date2 = [formatter dateFromString:[formatter stringFromDate:[NSDate date]]];

        }
        NSTimeInterval interval = [date1 timeIntervalSinceDate: date2];//[date1 timeIntervalSince1970] - [date2 timeIntervalSince1970];
        int hour = interval / 3600;
        int minute = (int)interval % 3600 / 60;

        NSLog(@"%@ %dh %dm", interval<0?@"-":@"+", ABS(hour), ABS(minute));

This code returns me difference of current time and the given time how can I proceed further.

Answer 1

You can do something like,

NSString *startTime = @"02:00 AM";
NSString *endTime = @"11:00 AM";


NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setDateFormat:@"hh:mm a"];
NSDate* fromTime = [timeFormat dateFromString:startTime];
NSDate* toTime = [timeFormat dateFromString:endTime];
NSDate *dateByAddingThirtyMinute ;
NSTimeInterval timeinterval = [toTime timeIntervalSinceDate:fromTime];
NSLog(@"time Int %f",timeinterval/3600);
float numberOfIntervals = timeinterval/3600;
NSLog(@"Start time %f",numberOfIntervals);

for(int iCount = 0;iCount < numberOfIntervals*2 ;iCount ++)
{
    dateByAddingThirtyMinute = [fromTime dateByAddingTimeInterval:1800];
    fromTime = dateByAddingThirtyMinute;
    NSString *formattedDateString;
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"hh:mm a"];
    formattedDateString = [dateFormatter stringFromDate:dateByAddingThirtyMinute];
    NSLog(@"Time after 30 min %@",formattedDateString);
}

In for loop I have taken numberOfIntervals*2 because time interval is 30 min , so 60/30 = 2 and your datebyAddingThirtyMinute is 1800 because 30 min = 1800 seconds. If you want time after every 10 minutes then it should 60/10 = 6, so it should numberOfIntervals*6 . And your datebyAddingThirtyMinute should be [fromTime dateByAddingTimeInterval:600];

Hope this will help :)

Answer 2

The most reliable way (also to consider daylight saving time changes) is to use the date math capabilities of NSCalendar .

Simply adding seconds with dateByAddingTimeInterval is not recommended at all.

NSDate *now = [NSDate date];
NSCalendar *cal = [NSCalendar currentCalendar];
// get minute and hour from now
NSDateComponents *nowComponents = [cal components:NSCalendarUnitHour | NSCalendarUnitMinute fromDate: now];
NSDate *currentDate;
// if current minutes is not exactly 0 or 30 get back to the past half hour
if (nowComponents.minute % 30 != 0) {
   NSInteger pastHalfHourIndex = nowComponents.minute / 30;
   nowComponents.minute = pastHalfHourIndex * 30;
   currentDate = [cal nextDateAfterDate:now matchingHour: nowComponents.hour minute: nowComponents.minute second: 0 options: NSCalendarMatchNextTime | NSCalendarSearchBackwards];
} else {
   currentDate = now;
}    
NSMutableArray<NSDate *>* dates = [NSMutableArray array];
// loop and add 30 minutes until the end time (10:30 pm) is reached
while (nowComponents.minute != 30 || nowComponents.hour != 22) {
  currentDate = [cal dateByAddingUnit:NSCalendarUnitMinute value: 30 toDate: currentDate options: NSCalendarMatchNextTime];
  [dates addObject:currentDate];
  nowComponents = [cal components:NSCalendarUnitHour | NSCalendarUnitMinute fromDate: currentDate];
}
NSLog(@"%@", dates);

Answer 3

Try this code it works for you

NSDateFormatter *datefrmt = [[NSDateFormatter alloc] init];
[datefrmt setDateFormat:@"hh:mm a"];
NSDate* startingTime = [datefrmt dateFromString:startTime];
NSDate* endingTime = [datefrmt dateFromString:endTime];
NSLog(@"Starting time is %@", startingTime);
NSLog(@"Stop time is %@", endingTime);    
NSDate * addingTimeInterval;    
addingTimeInterval = [startingTime dateByAddingTimeInterval:1800];    
NSLog(@"Required output is %@", addingTimeInterval);

Answer 4

I would first check if the given start time is AM or PM, after doing that, I would find the nearest (rounded up) 30m interval of time and simply add 30m to it and check whether or not I was at the given stop stop time, and if not increment a counter.

You could also add each 30m interval to a list if you wanted to keep track of and return that list to be printed out.

Answer 5

If you get the Start date is current date and time, then the end date is automatically set 30 mins use dateByAddingTimeInterval: , see my example,

NSDate *startDate = [NSDate date];

then set ending date is below code,

currentdate = startDate; //today
endingDate = [startDate dateByAddingTimeInterval:(60*60)/2]; // 60*60 is 1 hour. 

this above method automatically calculate current time to end time add 30 minutes.

hope its helpful