How to get the first day of a week for a date
this seems more easy at it is, since :
when the week starts with sunday, i need to get back the sunday date
if it starts on monday, i need to get the monday date
the input date is any date in week with time... i tried several approaches, but the edge case make it difficould
i made a function, which however doesn't work in 100% (not sure about the [components setDay: -weekday + 2];)
- (NSDate *)firstDateOfWeek {
NSCalendar * calendar = [NSCalendar currentCalendar];
NSDateComponents *weekdayComponents = [calendar components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:self];
// because sunday is 0, we need it to be 6
NSInteger weekday = (([weekdayComponents weekday] + 6) % 7);
NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:self];
[components setDay: -weekday + 2];
return [calendar dateFromComponents:components];
}
It is easier to use the rangeOfUnit calendar method, which handles "start of the week" correctly according to the current locale:
NSDate *date = your date;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *startOfWeek;
[calendar rangeOfUnit:NSWeekOfYearCalendarUnit
startDate:&startOfWeek
interval:NULL
forDate:date];
Using NSDateComponents, it would work as follows (assuming that a week has 7 days):
NSDate *date = your date;
NSDateComponents *comp = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSWeekdayCalendarUnit
fromDate:date];
NSDate *startOfDay = [calendar dateFromComponents:comp];
NSInteger diff = (NSInteger)[calendar firstWeekday] - (NSInteger)[comp weekday];
if (diff > 0)
diff -= 7;
NSDateComponents *subtract = [[NSDateComponents alloc] init];
[subtract setDay:diff];
NSDate *startOfWeek = [calendar dateByAddingComponents:subtract toDate:startOfDay options:0];
Related
I have to find next Sunday date (NSDate) from device's current date.
I have used below logic:
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *components = [calendar components:NSCalendarUnitWeekday | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay fromDate:self];
NSUInteger weekdayToday = [components weekday];
NSInteger daysToMonday = (8 - weekdayToday) % 7;
NSDate *weekEndPrev = [self dateByAddingTimeInterval:60*60*24*daysToMonday];
Here, in EST if time is near to 11 PM, I'm getting Monday as Weekend.
Let me know feasible solution. I have tried many options. Nothings works with 2 different timezones.
Thanks in Advance.
You need just to get the number of days you need and then just add them to your current date:
NSCalendar * calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDate * newDate = [calendar dateByAddingUnit:NSCalendarUnitDay value:value toDate:date options:0];
where value - is the number of days to add
Find current week Sunday Date first then add 7 days using NSDateComponents.
NSDate *today = [[NSDate alloc] init];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *weekdayComponents = [gregorian components:NSCalendarUnitWeekday fromDate:today];
NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
[componentsToSubtract setDay:(0 - ([weekdayComponents weekday] - 1))];
NSDate *sudayCurWeek = [gregorian dateByAddingComponents:componentsToSubtract toDate:today options:0];
NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
[offsetComponents setDay:7];
NSDate *nextSunday = [gregorian dateByAddingComponents:offsetComponents toDate:sudayCurWeek options:0];
NSLog(#"%#",nextSunday);
You can do this without any math, which is best left to NSCalendar as it handles daylight savings etc. First you need a calendar with the correct time zone. For example for IST:
NSCalendar *gc = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];
gc.timeZone = [NSTimeZone timeZoneWithName:#"IST"];
Then you can use nextDateAfterDate:matchingUnit:value:options: to find the start of the next Sunday after a given time. For example:
NSDate *start = ... // the time you wish to start from
NSDate *nextSunday =
[gc nextDateAfterDate:start
matching:UnitNSCalendarUnitWeekday // match based on weekday number
value:1 // Sunday = weekday 1
options:NSCalendarMatchNextTime // read the docs!
];
The returned date, nextSunday, will be the next Sunday at 00:00 in the timezone of the calendar, gc.
HTH
Finally, I got solution..
NSDateComponents *components = [[NSCalendar currentCalendar] componentsInTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"UTC"] fromDate:[NSDate date]]; // Pass date for which you want to find next Sunday
NSUInteger weekdayToday = [components weekday];
NSInteger daysToMonday = (8 - weekdayToday) % 7;
NSDate *weekEndPrev = [[NSDate date] dateByAddingTimeInterval:60*60*24*daysToMonday];
How can I create an NSDate with today's date and an hour, minutes, and seconds of 5, 0, and 0 respectively? I.e. the date will be 07/02/2010 05:00:00
//Gives us the current date
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorian components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:[NSDate date]];
[components setHour:5];
NSDate * date = [gregorian dateFromComponents:components];
[gregorian release];
Something along those lines should do the trick.
I am working on a Calender app and it's working fine when i navigate to next month as i am able to get the last day of the month and from where i am able to get the first day of coming month .but when i navigate to previous month i m not able to get the last month's first day.Is there any way to get first day of last month.
The following works fine for me
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *currentDate = [NSDate date];
NSDateComponents *components = [calendar components:(NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:currentDate];
components.month = components.month - 1;
components.day = 1;
NSDate *newDate = [calendar dateFromComponents:components];
This also works if your current month is january. NSDateComponents will automatically decrement the year and set the month to december.
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear
fromDate:[NSDate date]];
components.day = 1;
components.month = components.month - 1;
NSDate *lastmonthDay1 = [[NSCalendar currentCalendar] dateFromComponents: components];
NSLog(#"First day of last month====: %#", [lastmonthDay1 descriptionWithLocale:[NSLocale currentLocale]]);
You can do something like below....
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"UTC"]];
NSDateComponents *comp = [gregorian components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:[NSDate date]];
[comp setDay:1];
[comp setMonth:CurrentMonth];//previous month
[comp setYear:currentYear];
NSDate *firstDayOfMonthDate = [gregorian dateFromComponents:comp];
NSCalendar *cal1=[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps1 = [cal1 components:NSWeekdayCalendarUnit fromDate:firstDayOfMonthDate];
// 1 for mon 8 for sun
int startWithDay=[comps1 weekday]==1?8:[comps1 weekday];
//1 for monday
// 2 for tuesday and so on....
Let me know it is working or not!!!
Happy Coding!!!!
I want to determine day, month, and year of current date in iOS. I found this after a search on the net:
NSDate *date = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [calendar components:(NSDayCalendarUnit) fromDate:date];
NSInteger Day = [components day];
NSInteger month = [components month];
NSInteger year = [components year];
This code shows the day correct, but the year and month is not showing as it should be. It shows some digits like 2147483647. I could not find a solution so please help me correct the code I found, or write some new code which does what I need.
This line is the problem:
NSDateComponents *components = [calendar components:(NSDayCalendarUnit) fromDate:date];
It should be
NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:date];
I'm struggling to figure out how to dynamically create a date object for the most previous sunday at 12:00 AM
I was thinking I could get today's date and then subtract the current day of the week + 1 at which point I could just subtract the time of the day do get down to 12AM.
so far I have the current day of the week:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
int weekday = [comps weekday];
at which point I can get today's date and subtract the difference of weekday * seconds in a day. However, how can I get today's time in seconds ??
No need to manually calculate seconds (which is dangerous anyway because of daylight saving etc.). The following should do exactly what you want:
NSDate *today = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setLocale:[[NSLocale alloc] initWithLocaleIdentifier:#"en-US"]]; // force US locale, because other countries (e.g. the rest of the world) might use different weekday numbering
NSDateComponents *nowComponents = [calendar components:NSYearCalendarUnit | NSWeekCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:today];
[nowComponents setWeekday:1]; //Sunday
[nowComponents setHour:0]; // 12:00 AM = midnight (12:00 PM would be 12)
[nowComponents setMinute:0];
[nowComponents setSecond:0];
NSDate *previousSunday = [calendar dateFromComponents:nowComponents];
I'll leave worrying about transitions between daylight savings time to you:
NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [NSDate date];
NSLog(#"date %#", date);
NSDateComponents *componentsToday = [gregorian components:NSWeekdayCalendarUnit fromDate:date]; // NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit |
NSInteger days = componentsToday.weekday - 1;
NSLog(#"Days=%d", days);
NSDate *lastSunday = [date dateByAddingTimeInterval:-days*60*60*24];
NSLog(#"lastSunday %#", lastSunday);
NSDateComponents *componentsSunday = [gregorian components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:lastSunday];
[componentsSunday setHour:0];
[componentsSunday setMinute:0];
[componentsSunday setSecond:0];
NSDate *targetDate = [gregorian dateFromComponents:componentsSunday];
NSLog(#"TargetDate %#", targetDate);
#AndreasLey solution in Swift 2.0:
func getLastSunday() -> NSDate?
{
let today = NSDate();
let calendar : NSCalendar! = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)
calendar.locale = NSLocale(localeIdentifier: "en-US") // force US locale, because other countries (e.g. the rest of the world) might use different weekday numbering
let flags : NSCalendarUnit = [.Year , .Month, .Weekday, .WeekOfMonth, .Minute , .Second]
let nowComponents = calendar.components(flags, fromDate: today)
nowComponents.weekday = 1 //Sunday
nowComponents.hour = 0 // 12:00 AM = midnight (12:00 PM would be 12)
nowComponents.minute = 0
nowComponents.second = 0;
let previousSunday = calendar.dateFromComponents(nowComponents);
return previousSunday
}
This code is setting 12:00 am in your selected date from UIDatePicker.
NSDate *oldDateSelected = datePicker.date;
unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *comps = [calendar components:unitFlags fromDate:oldDateSelected];
comps.hour = 00;
comps.minute = 00;
comps.second = 44;
NSDate *newDate = [calendar dateFromComponents:comps];
return newDate;