This might be basic but i couldn't find a similar problem to clearly understand that.
I have some date which is this :
2015-07-19 12:00:00 +0000
then i am taking this date and try to get the hour of it with :
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *components = [gregorianCalendar components:NSCalendarUnitDay | NSCalendarUnitHour |NSCalendarUnitMinute | NSCalendarUnitMonth | NSCalendarUnitYear| NSCalendarUnitWeekday fromDate:tdate];
long hour=[components hour];
NSLog(#"-- %ld ",hour); //gives 15
Then i get the hour as 15 and not 12 as the original date .
The 3 hours different is i guess my GMT +3 .
How can i get 12 - the original date hour ?
adding this
[components setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"GMT"]];
didn't helped.
When i create that original date with components class, i do it in the exact way that i later do it again, so there shouldn't be any change in the GMT times.
To create the original date i do :
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay |NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitWeekday | NSCalendarUnitHour | NSCalendarUnitMinute fromDate:new];
[components setHour:12];
So, why when you extract it in the exact same way you dont get the same result ?
thanks .
When Using NSCalender and NSDateCompoment it will always translate date to your systemDate. If you want to have that Date invariant and meanwhile use DateCompoment to access components you need to remove the timeInterval between your systemeData to that date system(GMT in your case).
NSTimeZone* currentTimeZone = [NSTimeZone localTimeZone];
NSTimeInterval timeDiff = [currentTimeZone secondsFromGMTForDate:aGMTDate];
NSDate *gmtDate = [[NSDate alloc] initWithTimeInterval:(-timeDiff) sinceDate:[NSDate date]];
Does anyone know if there is a way to set the first day of the week on a NSCalendar, or is there a calendar that already has Monday as the first day of the week, instead of Sunday.
I'm currently working on an app that is based around a week's worth of work, and it needs to start on Monday, not Sunday. I can most likely do some work to work around this, but there will be a lot of corner cases. I'd prefer the platform do it for me.
Thanks in advance
Here's some the code that I'm using. it's saturday now, so what I would hope is that weekday would be 6, instead of 7. that would mean that Sunday would be 7 instead of rolling over to 0
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setFirstWeekday:0];
unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekCalendarUnit | NSWeekdayCalendarUnit;
NSDateComponents *todaysDate = [gregorian components:unitFlags fromDate:[NSDate date]];
int dayOfWeek = todaysDate.weekday;
Edit: This does not check the edge case where the beginning of the week starts in the prior month. Some updated code to cover this: https://stackoverflow.com/a/14688780/308315
In case anyone is still paying attention to this, you need to use
ordinalityOfUnit:inUnit:forDate:
and set firstWeekday to 2. (1 == Sunday and 7 == Saturday)
Here's the code:
NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
[gregorian setFirstWeekday:2]; // Sunday == 1, Saturday == 7
NSUInteger adjustedWeekdayOrdinal = [gregorian ordinalityOfUnit:NSWeekdayCalendarUnit inUnit:NSWeekCalendarUnit forDate:[NSDate date]];
NSLog(#"Adjusted weekday ordinal: %d", adjustedWeekdayOrdinal);
Remember, the ordinals for weekdays start at 1 for the first day of the week, not zero.
Documentation link.
This code constructs a date that is set to Monday of the current week:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *today = [NSDate date];
NSDate *beginningOfWeek = nil;
BOOL ok = [gregorian rangeOfUnit:NSWeekCalendarUnit startDate:&beginningOfWeek
interval:NULL forDate: today];
setFirstWeekday: on the NSCalendar object.
Sets the index of the first weekday for the receiver.
- (void)setFirstWeekday:(NSUInteger)weekday
Should do the trick.
In my opinion this settings should be dynamic according to the user locale.
Therefore one should use:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setLocale:[NSLocale currentLocale]];
This will cause the calendar to set the first week day according to the user locale automatically. Unless you are developing your app for a specific purpose/user locale (or prefer to allow the user to choose this day).
I've done it like this.
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *today = [NSDate date];
NSDateComponents *compForWeekday = [gregorian components:(NSWeekdayCalendarUnit) fromDate:today];
NSInteger weekDayAsNumber = [compForWeekday weekday]; // The week day as number but with sunday starting as 1
weekDayAsNumber = ((weekDayAsNumber + 5) % 7) + 1; // Transforming so that monday = 1 and sunday = 7
I had trouble with a lot of the answers here. . maybe it was just me. .
Here's an answer that works for me:
- (NSDate*)firstDayOfWeek
{
NSCalendar* cal = [[NSCalendar currentCalendar] copy];
[cal setFirstWeekday:2]; //Override locale to make week start on Monday
NSDate* startOfTheWeek;
NSTimeInterval interval;
[cal rangeOfUnit:NSWeekCalendarUnit startDate:&startOfTheWeek interval:&interval forDate:self];
return startOfTheWeek;
}
- (NSDate*)lastDayOfWeek
{
NSCalendar* cal = [[NSCalendar currentCalendar] copy];
[cal setFirstWeekday:2]; //Override locale to make week start on Monday
NSDate* startOfTheWeek;
NSTimeInterval interval;
[cal rangeOfUnit:NSWeekCalendarUnit startDate:&startOfTheWeek interval:&interval forDate:self];
return [startOfTheWeek dateByAddingTimeInterval:interval - 1];
}
Update:
As pointed out (elsewhere) by #vikingosegundo, in general its best to let the local determine which day is the start of the week, however in this case the OP was asking for the start of the week to occur on Monday, hence we copy the system calendar, and override the firstWeekDay.
The problem with Kris' answer is the edge case where the beginning of the week starts in the prior month. Here's some easier code and it also checks the edge case:
// Finds the date for the first day of the week
- (NSDate *)getFirstDayOfTheWeekFromDate:(NSDate *)givenDate
{
NSCalendar *calendar = [NSCalendar currentCalendar];
// Edge case where beginning of week starts in the prior month
NSDateComponents *edgeCase = [[NSDateComponents alloc] init];
[edgeCase setMonth:2];
[edgeCase setDay:1];
[edgeCase setYear:2013];
NSDate *edgeCaseDate = [calendar dateFromComponents:edgeCase];
NSDateComponents *components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:edgeCaseDate];
[components setWeekday:1]; // 1 == Sunday, 7 == Saturday
[components setWeek:[components week]];
NSLog(#"Edge case date is %# and beginning of that week is %#", edgeCaseDate , [calendar dateFromComponents:components]);
// Find Sunday for the given date
components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:givenDate];
[components setWeekday:1]; // 1 == Sunday, 7 == Saturday
[components setWeek:[components week]];
NSLog(#"Original date is %# and beginning of week is %#", givenDate , [calendar dateFromComponents:components]);
return [calendar dateFromComponents:components];
}
I see misunderstanding in the other messages. The first weekday, whichever it is, has number 1 not 0. By default Sunday=1 as in the "Introduction to Date and Time Programming Guide for Cocoa: Calendrical Calculations":
"The weekday value for Sunday in the Gregorian calendar is 1"
For the Monday as a first workday the only remedy I have is brute force condition to fix the calculation
NSCalendar *cal=[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [cal components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
// set to 7 if it's Sunday otherwise decrease weekday number
NSInteger weekday=[comps weekday]==1?7:[comps weekday]-1;
Below also covers the edge case,
- (NSDate *)getFirstDayOfTheWeekFromDate:(NSDate *)givenDate
{
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:givenDate];
[components setWeekday:2]; // 1 == Sunday, 7 == Saturday
if([[calendar dateFromComponents:components] compare: curDate] == NSOrderedDescending) // if start is later in time than end
{
[components setWeek:[components week]-1];
}
return [calendar dateFromComponents:components];
}
You can just change .firstWeekday of the calendar.
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
calendar.firstWeekday = 2;
Then use rangeOfUnit:startDate:interval:forDate: to get the first day
NSDate *startOfWeek;
[calendar rangeOfUnit:NSCalendarUnitWeekOfYear startDate:&startOfWeek interval:nil forDate:[NSdate date]];
Try this:
NSCalendar *yourCal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]
[yourCal setFirstWeekday:0];
Iv found out the way to display any weekday name using nscalender..using the following code..
Just open your console from xcode menu bar to see the results.Copy Paste the following code in your viewDidLoad method to get the first day of the week
NSDate *today = [NSDate date];
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"MM/dd/yyyy :EEEE"];
NSString *dateString = [dateFormat stringFromDate:today];
NSLog(#"date: %#", dateString);
[dateFormat release];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorian components:NSWeekdayCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:today];
[components setDay:([components day]-([components weekday]-1))];
NSDate *beginningOfWeek = [gregorian dateFromComponents:components];
NSDateFormatter *dateFormat_first = [[NSDateFormatter alloc] init];
[dateFormat_first setDateFormat:#"MM/dd/yyyy :EEEE"];
NSString *dateString_first = [dateFormat_first stringFromDate:beginningOfWeek];
NSLog(#"First_date: %#", dateString_first);
The Output will be:
date: 02/11/2010 :Thursday
First_date: 02/07/2010 :Sunday
since i had run this program on 2/11/2010 u will get the desired output depending on the current date.
Similarly if u want to get the first working day of the week i.e Monday's date then just modify the code a bit:
CHANGE :[components setDay:([components day]-([components weekday]-1))];
TO
[components setDay:([components day]-([components weekday]-2))];
to get Mondays date for that week..
Similarly u can try to find the date of any of seven workdays by changing the integer -1,-2 and so on...
Hope u r question is answered..
Thanks,
Bonson Dias
The ISO 8601 calendar appears to have it's first weekday set to monday by default.
Using the Calendar nextWeekend (iOS 10 or later) and ordinality (thanks #kris-markel). I've gotten Monday as first of the week for the en_US calendar.
Here is an example of it with fallback to firstWeekday:
extension Calendar {
var firstWorkWeekday: Int {
guard #available(iOS 10.0, *) else{
return self.firstWeekday
}
guard let endOfWeekend = self.nextWeekend(startingAfter: Date())?.end else {
return self.firstWeekday
}
return self.ordinality(of: .weekday, in: .weekOfYear, for: endOfWeekend) ?? self.firstWeekday
}
}
The Swift solution (note, use .yearForWeekOfYear, not .year):
let now = Date()
let cal = Calendar.current
var weekComponents = cal.dateComponents([.yearForWeekOfYear, .weekOfYear,
.weekday], from: now)
//weekComponents.weekday = 1 // if your week starts on Sunday
weekComponents.weekday = 2 // if your week starts on Monday
cal.date(from: weekComponents) // returns date with first day of the week
… is there a calendar that already has Monday as the first day of the week, instead of Sunday.
Someday, there will be.
My simple way of doing this is to get Monday = 0, Sunday = 6:
NSDateComponents *dateComponents = [[NSCalendar currentCalendar] components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
NSInteger dayNumStartingFromMonday = ([dateComponents weekday] - 2 + 7) % 7; //normal: Sunday is 1, Monday is 2
I want to get difference between dates skipping time means if one date is 13 Jan 2012 - 11 pm and other date is 14 Jan 2012 - 12 am,then difference should be 1 day not 0 day.I mean I want difference between date only, 14 Jan 2012 - 13 Jan 2012, skipping time. I know I can use NSDate api to calculate difference but the problem is it consider time also.So I thought while calculating difference I will skip time but I do not know how to skip time because if I use NSDateFormatter it will return string not date.Please help me what I can do?
Thanks in advance!
What you need to do is get the NSDateComponents of each date first. Once you do that you can compare the 'day' component to get you difference.
NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[cal setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSDate *date1 = ....;
NSDate *date2 = ....;
NSDateComponents *comps1 = [cal components:NSDayCalendarUnit|NSYearCalendarUnit|NSMonthCalendarUnit fromDate:date1];
NSDateComponents *comps2 = [cal components:NSDayCalendarUnit|NSYearCalendarUnit|NSMonthCalendarUnit fromDate:date2];
date1 = [cal dateFromComponents:comps1];
date2 = [cal dateFromComponents:comps2];
NSDateComponents *diffComps = [cal components:NSDayCalendarUnit fromDate:date1 toDate:date2 options:0];
NSLog(#"Days diff = %d", diffComps.day);
The date API can be kind of weird to wrap your head around, but once you do it is quite powerful.
I am trying to produce an NSDate with fixed hour and minutes. I need this to make an equal comparison with other date stored in CoreData.
So far I wrote this code:
NSDate date = [NSDate date];
unsigned int flags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDateComponents* components = [calendar components:flags fromDate:date];
NSDate* newDate = [calendar dateFromComponents:components];
however with a breakpoint in xcode4 I can see the values:
Printing description of date:
2012-01-10 11:20:47 +0000
Printing description of newDate:
2012-01-09 23:00:00 +0000
Why newDate is one day back in respect of date ?
/* EDIT */
I also have tried to set manually all the components, but calendar dateFromComponents always give back same one hour back date, seems ignoring the components.
components.hour=0;
components.minute=0;
components.second=0;
components.timeZone=[NSTimeZone localTimeZone];
This is the description of component after being set:
<NSDateComponents: 0x7464de0>
TimeZone: Europe/Rome (CET) offset 3600
Calendar Year: 2012
Month: 1
Day: 10
Hour: 0
Minute: 0
Second: 0
which is exactly what I would like to have, but the calculated date with this component is still
Printing description of newDate:
2012-01-09 23:00:00 +0000
I wonder why I cannot get a precise NSDate even with specifying all the components in an NSDateComponents. Just because NSCalendar is ignoring my requirements, what's the meaning of components ?
What am I doing wrong ?
I guess you are +01:00 time zone. Actually the NSDate always gives values in GMT. So if it is Jan 10th, 00:00, then at the same time GMT time is Jan 9th, 23:00.
Even, while printing the following line
2012-01-10 11:20:47 +0000,
it should have printed 1 hour less than your current time. Please check.
Use this....
NSDate *date = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setLocale:[NSLocale currentLocale]];
NSDateComponents *nowComponents = [gregorian components:NSYearCalendarUnit | NSWeekCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:date];
NSDate* newDate = [gregorian dateFromComponents:nowComponents];
NSLog(#"%#\n%#",date,newDate);
You may have problems with time zones, try setting a time zone for the calendar.
I have a date picker.
After choosing a time from this I would like to get the dates of the next 64 Mondays.
How would I go about writing a method to take a date and return an NSArray of NSDates for the next 64 Mondays from that date
for e.g.
I picked time 6:45 pm from date picker then I want to fetch next 64 mondays with there time set to that time.
Example (ARC):
NSDate *pickerDate = [NSDate date];
NSLog(#"pickerDate: %#", pickerDate);
NSDateComponents *dateComponents;
NSCalendar *calendar = [NSCalendar currentCalendar];
dateComponents = [calendar components:NSWeekdayCalendarUnit fromDate:pickerDate];
NSInteger firstMondayOrdinal = 9 - [dateComponents weekday];
dateComponents = [[NSDateComponents alloc] init];
[dateComponents setDay:firstMondayOrdinal];
NSDate *firstMondayDate = [calendar dateByAddingComponents:dateComponents toDate:pickerDate options:0];
dateComponents = [[NSDateComponents alloc] init];
[dateComponents setWeek:1];
for (int i=0; i<64; i++) {
[dateComponents setWeek:i];
NSDate *mondayDate = [calendar dateByAddingComponents:dateComponents toDate:firstMondayDate options:0];
NSLog(#"week#: %i, mondayDate: %#", i, mondayDate);
}
NSLog output:
pickerDate: 2011-12-09 20:38:25 +0000
week#: 0, mondayDate: 2011-12-12 20:38:25 +0000
week#: 1, mondayDate: 2011-12-19 20:38:25 +0000
week#: 2, mondayDate: 2011-12-26 20:38:25 +0000
week#: 3, mondayDate: 2012-01-02 20:38:25 +0000
-the remaining 60 here-
Start with the NSDate from the picker, and keep adding 24*60*60 seconds to it until it's a Monday. Add the resulting date to the result. Continue adding 7*24*60*60 seconds to the last date you added and pushing the result onto the return list until you have all 64 Mondays. Here is how you tell if a NSDate falls on Monday:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents =[gregorian components:NSWeekdayCalendarUnit fromDate:dateOfInterest];
NSInteger weekday = [weekdayComponents weekday];
if (weekday == 2) ... // 2 represents Monday
EDIT: DaveDeLong pointed out a deficiency in the above algorithm: it will shift the time two times on the days of changing to daylight savings time. Instead of counting seconds manually, use this code to add a day to NSDate:
NSDate *currentDate = [NSDate date];
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:1]; // Add 1 when searching for the next Monday; add 7 when iterating 63 times
NSDate *date = [gregorian dateByAddingComponents:comps toDate:currentDate options:0];
[comps release];
You can use NSCalendar to determine what day of the week today (at the chosen time) is; bump it up to get to the next Monday, and then bump that by by 7 days 63 times to get the Mondays you seem to want.