This question already has answers here:
Unexpected value from NSDate
(2 answers)
Closed 6 years ago.
There are many issues similar to mine, but something goes wrong. Why function setDay sets to 1 day less? Where did I go wrong?
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDate *today = [NSDate date];
NSLog(#"today date = %#", today);
NSDateComponents *components = [calendar components:(NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear ) fromDate:today];
[components setDay:1];
NSLog(#"modified date = %#", [calendar dateFromComponents:components]);
Log:
today date = 2016-07-04 10:01:30 +0000
modified date = 2016-06-30 21:00:00 +0000
Modified date should be 2016-07-01
Likely it is 2016-07-01, 24:00 GMT. NSLog() prints it out for GMT, not your locale time.
See here: Unexpected value from NSDate
You should add NSCalendarUnitHour in NSDateComponents like this then then you get correct date
NSDateComponents *components = [calendar components:(NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear |NSCalendarUnitHour) fromDate:today];
Try this code:
NSDateFormatter* df = [[NSDateFormatter alloc] init];
[df setTimeZone:[NSTimeZone defaultTimeZone]]; // your time 00:00:00
[df setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSLog(#"modified date = %#", [df stringFromDate:[calendar dateFromComponents:components]]); // Date format NSString
Related
When I pass the [NSDate date] to NSDateComponents , then pass back after the weekday modified, I always got the hour 16:00:00 . Why ?
Code belows:
{
NSCalendar *calendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDate *now = [NSDate date];
NSLog(#"now = %#",now);
NSDateComponents *firstDayOfWeek = [calendar components:NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitWeekday fromDate:now];
firstDayOfWeek.weekday = 1; // Monday as first day of week
NSDate *firstDayOfWeekDate = [calendar dateFromComponents:firstDayOfWeek];
NSLog(#"first day = %#", firstDayOfWeekDate);
}
{
NSCalendar *calendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDate *now = [NSDate date];
NSLog(#"now = %#",now);
NSDateComponents *firstDayOfWeek = [calendar components:NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitWeekday | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond fromDate:now];
firstDayOfWeek.weekday = 1; // Monday as first day of week
firstDayOfWeek.hour = 1;
firstDayOfWeek.minute = 1;
firstDayOfWeek.second = 1;
NSDate *firstDayOfWeekDate = [calendar dateFromComponents:firstDayOfWeek];
NSLog(#"first day = %#", firstDayOfWeekDate);
}
And the output is :
now = 2016-01-18 03:14:08 +0000
first day = 2016-01-17 16:00:00 +0000
now = 2016-01-18 03:14:08 +0000
first day = 2016-01-17 17:01:01 +0000
Why the hour begins with 16 ?
NSDateComponents isn't making it 16:00:00. It's making it midnight in your current timezone. But the NSLog is showing you the equivalent GMT time. That's what the +0000 means: e.g. GMT +00:00.
Bottom line, if you want to see the resulting NSDate object in your local time zone, you should use NSDateFormatter.
This is due to timezone.
Try to add NSDateFormatter before you output the date with NSLog, e.g.
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setLocale:[NSLocale currentLocale]];
[dateFormatter setDateStyle:NSDateFormatterShortStyle];
[dateFormatter setTimeStyle:NSDateFormatterLongStyle];
NSString *dateDisplay = [dateFormatter stringFromDate:firstDayOfWeekDate];
NSLog(#"first day = %#",dateDisplay);
You can refer this article for more examples.
I know there's a few questions already on this but I keep running into the same error regardless of what I do to my code. I am working in the simulator, I have location set to my long/lat. When I try to convert the current date to zero hours, minutes, seconds I always get this result:
2015-07-10 08:53:19.868 xxxxxxxxxxxxxxxxx[2184:7462272] Today at start of day:2015-07-10 04:00:00 +0000
Here's my code:
NSDate* today = [[NSDate alloc] init];
NSCalendar* currentCalendar = [NSCalendar currentCalendar];
NSDateComponents* dateComponents = [currentCalendar components:NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitYear fromDate:today];
NSInteger thisMonth = [dateComponents month];
NSInteger thisDay = [dateComponents day];
NSInteger thisYear = [dateComponents year];
NSDateComponents* dayComponents = [[NSDateComponents alloc] init];
[dayComponents setDay:thisDay];
[dayComponents setMonth:thisMonth];
[dayComponents setYear:thisYear];
NSDate* todayAtMidnight = [currentCalendar dateFromComponents:dayComponents];
NSLog(#"Today at start of day:%#", todayAtMidnight);
Even if add
[dayComponents setHour:0]; the hour still comes out as 4.
What am I doing wrong?
To get the beginning of today you can use
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
fromDate:[NSDate date]];
[calendar setTimeZone:[NSTimeZone timeZoneWithName:#"GMT"]];
NSLog(#"date %#", [calendar dateFromComponents:components]);
Make sure you have the correct timezone
2015-07-10 04:00:00 +0000 is UTC, not your local timezone.
To display it in your local timezone, use an NSDateFormatter:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.dateFormat = #"yyyy-MM-dd HH:mm";
[dateFormatter setTimeZone:[NSTimeZone systemTimeZone]];
NSLog([dateFormatter stringFromDate:todayAtMidnight]);
Use NSDateFormatter as follow because system timezone is UTC:
NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
[formatter setTimeZone:[NSTimeZone timeZoneWithName:#"GMT"]];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate * curDate = [formatter dateFromString:[NSDate date]];
Then you'll get 2015-07-10 00:00:00.
This question already has an answer here:
NSDateFormatter - 1 day incorrect?
(1 answer)
Closed 7 years ago.
I try to get first date for the current month from [NSDate new]. My problem is that instead of 2015/06/01 I always receive 2015/05/31. I even try to convert string 20150601 to NSDate and I still receive 2015/05/31.
Here is my CODE (for the second element):
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:#"yyyyMMdd"];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
currentMonth = [dateFormatter dateFromString:#"20150601"];
The result is:
(lldb) print currentMonth
(__NSDate *) $0 = 0x79e64820 2015-05-31 21:00:00 UTC
EDIT:
Ok, I understand my mistake - I don't check correctly result of my operations. They always result in UTC.
10x, for answer and all comments. I will be more careful next time.
NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorian components:(NSEraCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit) fromDate:today];
components.day = 1;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
NSTimeZone *zone = [NSTimeZone localTimeZone];
[formatter setTimeZone:zone];
[formatter setDateFormat:#"yyyyMMdd"];
NSDate *dayOneInCurrentMonth = [gregorian dateFromComponents:components];
NSString *currentMonth = [formatter stringFromDate:dayOneInCurrentMonth];
NSLog(#"%#",currentMonth);
Output
2015-06-08 14:07:30.924 NSDATEDemo[1943:39838] 20150601
Create NSDateComponents from [NSDate date], set the current day to 1 and re-create your NSDate object:
- (NSDate *) dateAtStartOfMonth
{
//Not tested!!!
NSDateComponents *comp = [[NSCalendar currentCalendar] components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:[NSDate date]];
[comp setDay:1];
return [[NSCalendar currentCalendar] dateFromComponents:comp];
}
If I have a string representing a time, say "10:45 am", and do the following to parse the string:
NSDateFormatter *dateFormat;
dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"h:mm a"];
NSLog(#"%#", [dateFormat dateFromString:#"10:45 AM"]);
I would get this logged:
2013-09-09 17:52:30.416 TimeTest[49491:a0b] 2000-01-01 15:45:00 +0000
How can I create an NSDate for the current day at the given time? I tried this
NSDate *date = [NSDate date];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"h:mm a"];
NSDate *time = [formatter dateFromString:#"10:45 AM"];
NSDateComponents *timeComponents = [[NSCalendar currentCalendar] components:(NSHourCalendarUnit | NSMinuteCalendarUnit ) fromDate:time];
NSDateComponents *dateComponents = [[NSCalendar currentCalendar] components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:date];
NSDateComponents *newComponents = [[NSDateComponents alloc]init];
newComponents.timeZone = [NSTimeZone systemTimeZone];
[newComponents setDay:[dateComponents year]];
[newComponents setMonth:[dateComponents month]];
[newComponents setYear:[dateComponents year]];
[newComponents setHour:[timeComponents hour]];
[newComponents setMinute:[timeComponents minute]];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *combinedDate = [gregorianCalendar dateFromComponents:newComponents];
NSLog(#"%#", combinedDate);
with the result
2013-09-09 19:57:14.506 TimeTest[49712:a0b] 2019-03-06 15:45:00 +0000
How should I go about this?
I'm not exactly sure what you are looking for. For what I understand, you want to build a date with the current year, month and day, but with your supplied time by parsing it from a string.
If that is the case, as others have pointed out, you need to play with NSDateComponents.
Based on your code I wrote these lines. They should build a date by merging two dates. The current one and the one you parsed.
// Get the full current date
NSDate *date = [NSDate date];
// Get the current calendar
NSCalendar *calendar = [NSCalendar currentCalendar];
// Split the date into components but only take the year, month and day and leave the rest behind
NSDateComponents *dateComponents = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:date];
// Build the date formatter
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"h:mm a"];
// Convert the string time into an NSDate
NSDate *time = [formatter dateFromString:#"10:45 AM"];
// Split this one in components as well but take the time part this time
NSDateComponents *timeComponents = [[NSCalendar currentCalendar] components:(NSHourCalendarUnit | NSMinuteCalendarUnit ) fromDate:time];
// Do some merging between the two date components
dateComponents.hour = timeComponents.hour;
dateComponents.minute = timeComponents.minute;
// Extract the NSDate object again
NSDate *result = [calendar dateFromComponents:dateComponents];
// Check if this was what you where looking for
NSLog(#"%#",result);
Please be aware that this sample code is by far non-optimized. There are more crisp ways to obtain what you are looking for by using time intervals, but I felt like you wanted a dirty simple example on how to do components copy and paste and then extracting dates.
This will create a date for the beginning of the day in the current time zone.
NSDate *today = [NSDate date];
NSTimeInterval interval;
NSCalendar *cal = [NSCalendar currentCalendar];
[cal rangeOfUnit:NSDayCalendarUnit
startDate:&today
interval:&interval
forDate:today];
Now we add the time:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
// I have to set the locale to posix_en_us, as my system is using 24hour style as default
dateFormatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:#"en_US_POSIX"];
[dateFormatter setDateFormat:#"hh:mm a"];
NSDate *time = [dateFormatter dateFromString:#"10:45 AM"];
NSDateComponents *comps = [cal components:(NSHourCalendarUnit | NSMinuteCalendarUnit)
fromDate:time];
NSDate *dateAndTime = [cal dateByAddingComponents:comps
toDate:today
options:0];
dateAndTime will now be todays date with 10:45 am in the local timezone.
controlling in the debugger:
po dateAndTime
$0 = 0x41b7df138c00000d 2013-09-10 08:45:00 +0000
This is correct, as my timezone is 2 hours ahead to GMT, as we still have summer time.
I have the following code to set the time on a date to 0 hours, 0 minutes, 0 seconds by using the YEAR, MONTH and DAY components from the date to construct a new one:
NSDate *date = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:date];
NSDate *newDate = [gregorian dateFromComponents:comps];
NSLog(#"date: %#, newDate: %#", date, newDate);
The output is:
date: 2012-11-06 11:44:09 +0000, newDate: 2012-11-05 23:00:00 +0000
but I was expecting the new date to be: 2012-11-06 00:00:00 +0000
What's happening that I should know of?
NSLog shows the dates using -[NSDate description] which, in turn, converts the absolute time stored in the NSDate to a string. This conversion is done using UTC as the time zone.
For you case it's probably best to do the date calculations in UTC as well. To do so adjust the calendar object that does the calculations:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"UTC"]];
See this answer for a similar Stack Overflow question.
This should solve your issue with daylight savings:
NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
[formatter setCalendar:[NSCalendar currentCalendar]];
[formatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"UTC"]];
NSString *string = [formatter stringFromDate:[NSDate date]];