How to calculate remaining Days, Hours, Mins and seconds from given date? - ios

Question

In my app I need to get the days, hours, minutes and seconds from a given date which is coming from JSON response. Below is the date and time i'm getting:
"date_time" = "2017-01-31 08:30:00";
and need to calculate remaining like days: 6 hours: 18 minutes: 24 seconds: 30
End date will be today's date. I tried below code but it is giving me days in minus (I think it takes UTC timezone) and also tried many answers on SO.
NSString *start = [[self.eventsArray valueForKey:#"date_time"]objectAtIndex:0];
NSDateFormatter *date = [[NSDateFormatter alloc] init];
[date setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSString *end = [date stringFromDate:[NSDate date]];
NSDateFormatter *f = [[NSDateFormatter alloc] init];
[f setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate *startDate = [f dateFromString:start];
NSDate *endDate = [f dateFromString:end];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *components = [gregorianCalendar components:NSCalendarUnitDay
fromDate:startDate
toDate:endDate
options:0];
NSLog(#"day : %ld H: %ld M : %ld S:%ld", [components day], (long)[components hour],(long)[components minute],(long)[components second]);
Somebody please help i'm stuck.

Answer 1

You are making mistake here, your fromDate should be the today date ie [NSDate date] and with toDate will be your startDate. So your code should be something like this.
NSString *end = [[self.eventsArray valueForKey:#"date_time"]objectAtIndex:0];
NSDateFormatter *date = [[NSDateFormatter alloc] init];
[date setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDateFormatter *f = [[NSDateFormatter alloc] init];
[f setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
//Start date
NSDate *startDate = [NSDate date];
NSDate *endDate = [f dateFromString:end];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *components = [gregorianCalendar components:NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond
fromDate:startDate
toDate:endDate
options:0];
NSLog(#"day : %ld H: %ld M : %ld S:%ld", [components day], (long)[components hour],(long)[components minute],(long)[components second]);

Answer 2

Call below method and pass your date
+(NSMutableString*) timeLeftSinceDate: (NSDate *) dateT {
NSMutableString *timeLeft = [[NSMutableString alloc]init];
NSDate *today10am = [NSDate date];
today10am = [self getPickerDateForString:[self getPickerDateForDate:today10am]];
NSInteger seconds = [today10am timeIntervalSinceDate:dateT];
NSInteger days = (int) (floor(seconds / (3600 * 24)));
if(days) seconds -= days * 3600 * 24;
NSInteger hours = (int) (floor(seconds / 3600));
if(hours) seconds -= hours * 3600;
NSInteger minutes = (int) (floor(seconds / 60));
if(minutes) seconds -= minutes * 60;
if(days) {
[timeLeft appendString:[NSString stringWithFormat:#"%ld Days ago", (long)days]];
}else if(hours) {
[timeLeft appendString:[NSString stringWithFormat: #"%ld h ago", (long)hours]];
}else if(minutes) {
[timeLeft appendString: [NSString stringWithFormat: #"%ld m ago",(long)minutes]];
}else if(seconds) {
[timeLeft appendString:[NSString stringWithFormat: #"Just now"]];
}
return timeLeft;
}
+ (NSString *)getPickerDateForDate:(NSDate *)dateVal
{
NSString * stringVal;
if (!dateFormatter)
{
dateFormatter = [[NSDateFormatter alloc] init];
}
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
dateFormatter.timeZone = [NSTimeZone timeZoneWithName:#"UTC"];
stringVal = [dateFormatter stringFromDate:dateVal];
return stringVal;
}
+ (NSDate *)getPickerDateForString:(NSString *)dateString
{
NSDate * stringVal;
if (!dateFormatter)
{
dateFormatter = [[NSDateFormatter alloc] init];
}
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
dateFormatter.timeZone = [NSTimeZone systemTimeZone];
stringVal = [dateFormatter dateFromString:dateString];
return stringVal;
}