How to find weekday from today's date using NSDate? - objective-c

I know that I can figure out today's date by [NSDate date]; but how would I find out today day of the week, like Saturday, Friday etc.
I know that %w can be used in NSDateFormatter, but I don't know to use it.


NSCalendar* cal = [NSCalendar currentCalendar];
NSDateComponents* comp = [cal components:NSCalendarUnitWeekday fromDate:[NSDate date]];
return [comp weekday]; // 1 = Sunday, 2 = Monday, etc.
See #HuguesBR's answer if you just need the weekday without other components (requires iOS 8+).
NSInteger weekday = [[NSCalendar currentCalendar] component:NSCalendarUnitWeekday
fromDate:[NSDate date]];
(If you don't get a correct answer, check if you have mistyped NSCalendarUnitWeekday with other week-related components like NSCalendarUnitWeekdayOrdinal, etc.)
Swift 3:
let weekday = Calendar.current.component(.weekday, from: Date())
// 1 = Sunday, 2 = Monday, etc.


If someone is interested in a Swift solution, then use:
import Foundation
let weekday = NSCalendar.current.component(.weekday, from: Date())
print(weekday) // => prints the weekday number 1-7 (Sunday through Saturday)
See the demo.
Update: fixed to work in Swift 3


This is updated version valid for iOS 8
NSCalendar* currentCalendar = [NSCalendar currentCalendar];
NSDateComponents* dateComponents = [currentCalendar components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
return [dateComponents weekday];


Shorter version
NSCalendarUnit dayOfTheWeek = [[NSCalendar currentCalendar] component:NSCalendarUnitWeekday fromDate:yourDate];


let today = Date()
let day = Calendar.current.dateComponents([.weekday], from: today).weekday
if ( day == 5)
{
yourText.text = "Thursday"
}

Related

Extract week of year with components / set Monday as first weekday

I am developing an application, in which I repeatedly have to calculate in which week of the year a certain date is.
I know it sounds very simple. I would just use a date formatter if Sunday was not rated as next week, which annoys me.
So I decided to use date components. I have modified the calendar object, so the first weekday is Monday:
+ (NSInteger) getNumberOfWeekOfYearFromDate:(NSDate *)entryDate{
NSCalendar *calendar = [NSCalendar currentCalendar];
[calendar setFirstWeekday: 2];
NSDateComponents *components = [calendar components:NSWeekCalendarUnit | NSYearForWeekOfYearCalendarUnit | NSYearCalendarUnit fromDate:entryDate];
NSInteger weekOfYear = [components weekOfYear];
return weekOfYear;
}
Unfortunately the return values are large numbers like "2147483647". What am I doing wrong? I did not find any solution when I was searching the web.
Cheers and thanks in advance

Try this:
+ (NSInteger) getNumberOfWeekOfYearFromDate:(NSDate *)entryDate{
NSCalendar *calendar = [NSCalendar currentCalendar];
[calendar setFirstWeekday: 2];
NSDateComponents *components = [calendar components:
NSCalendarUnitWeekOfYear | NSCalendarUnitYear fromDate:entryDate];
NSInteger weekOfYear = [components weekOfYear];
return weekOfYear;
}

How to get first day of the week in IOS [duplicate]

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

NSDate off while calculating last monday's date

I have a problem with my function that is supposed to retrieve this week's monday's date.
Sometimes it's a day off:
+(NSDate *) lastMondayBeforeDate:(NSDate*)timeStamp {
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps =
[gregorian components:NSWeekdayCalendarUnit fromDate:timeStamp];
NSInteger weekday = [comps weekday];
weekday = weekday==1 ? 6 : weekday-2;
NSTimeInterval secondsSinceMondayMidnight =
(NSUInteger) [timeStamp timeIntervalSince1970] % 60*60*24 +
weekday * 60*60*24;
NSLog(#"MONDAY's DATE-----------%#", [timeStamp dateByAddingTimeInterval:-secondsSinceMondayMidnight]);
return [timeStamp dateByAddingTimeInterval:-secondsSinceMondayMidnight];
}

Apple has code demonstrating how to do almost exactly this. They are targeting the Sunday of the week instead of Monday, but you can just add 1 in the appropriate place to adjust.
You definitely don't want to be doing things like 60*60*24 and computing seconds to adjust by. For example, days can have more or less than 24 hours due to changes in Daylight Saving Time.

Objective-c get day of week in number starting with Monday, NOT Sunday

I'm making my custom calendar view for an app for the European market. In a function I should get number of day of week... I do, but it returns the number of the day of week starting with Sunday. How should I hardcode returning this number starting with Monday?
Thanks
Here is what I have so far:
-(int)getWeekDay:(NSDate*)date_
{
NSLocale *frLocale = [[NSLocale alloc] initWithLocaleIdentifier:#"fr_FR"];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setLocale:frLocale];
NSDateComponents *comps = [gregorian components:NSWeekdayCalendarUnit fromDate:date_];
int weekday = [comps weekday];
NSLog(#"Week day is %i", weekday);
return weekday;
}

You should use [NSCalendar setFirstWeekday:] to do this.

The best way to do this would be to use [NSCalendar setFirstWeekday:], as Joshua said in his answer.
Otherwise, you can do integer arithmetic. Vova's method is straightforward:
if (weekday>1)
weekday--;
else
weekday=7;
This one below works too, although it's a bit confusing:
int europeanWeekday = ((weekday + 5) % 7) + 1;

number of calendarweeks for year (ISO 8601 definition)

how can I calculate the number of calendarweeks in objective-C for a given year.
I tried:
[calendar rangeOfUnit:NSWeekOfYearCalendarUnit inUnit: NSYearCalendarUnit forDate: [NSDate date]].length
but it returns 54.
Thanks

You are using NSWeekOfYearCalendarUnit, so you must use the corresponding larger unit which is NSYearForWeekOfYearCalendarUnit.
NSCalendar *calendar = [NSCalendar currentCalendar];
calendar.firstWeekday = 2;
calendar.minimumDaysInFirstWeek = 4;
int n = [calendar rangeOfUnit:NSWeekOfYearCalendarUnit inUnit:NSYearForWeekOfYearCalendarUnit forDate: [NSDate date]].length;
NSLog(#"%d", n); // 52
Finally, note that both NSWeekOfYearCalendarUnit and NSYearForWeekOfYearCalendarUnit are iOS 5.0 and OS X 10.7 only.
Edit
As noted by #lnafziger, if you use a date that is in a calendar week from the previous year or next year such as 1/1/2016, this will calculate the number of weeks in that year (2015 in the example), and not the actual year of the date (2016 in the example). If this is not what you want, you can change the date like follows:
NSDateComponents *components = [calendar components:NSYearCalendarUnit fromDate:date];
components.month = 3;
date = [calendar dateFromComponents:components];

After a significant amount of testing, here is a function which will return it for any year:
- (NSUInteger)iso8601WeeksForYear:(NSUInteger)year {
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *firstThursdayOfYearComponents = [[NSDateComponents alloc] init];
[firstThursdayOfYearComponents setWeekday:5]; // Thursday
[firstThursdayOfYearComponents setWeekdayOrdinal:1]; // The first Thursday of the month
[firstThursdayOfYearComponents setMonth:1]; // January
[firstThursdayOfYearComponents setYear:year];
NSDate *firstThursday = [calendar dateFromComponents:firstThursdayOfYearComponents];
NSDateComponents *lastDayOfYearComponents = [[NSDateComponents alloc] init];
[lastDayOfYearComponents setDay:31];
[lastDayOfYearComponents setMonth:12];
[lastDayOfYearComponents setYear:year];
NSDate *lastDayOfYear = [calendar dateFromComponents:lastDayOfYearComponents];
NSDateComponents *result = [calendar components:NSWeekCalendarUnit fromDate:firstThursday toDate:lastDayOfYear options:0];
return result.week + 1;
}
Basically, per the spec, the total number of weeks is the same as the total number of Thursday's in the year, which is what this calculates.
I have tested it for the entire 400 year cycle (starting in the year 0 and the year 2000) and all cases match the spec.