dateByAddingDays is not safe for Daylight Saving Time switch.
I have an issue related this dateByAddingDays on Nov 3rd, and just realized this date is DST End Date.

What do you think if we using NSDateComponent for add days calculation?

Original :

- (NSDate *) dateByAddingDays: (NSInteger) dDays
{
    NSTimeInterval aTimeInterval = [self timeIntervalSinceReferenceDate] + D_DAY * dDays;
    NSDate *newDate = [NSDate dateWithTimeIntervalSinceReferenceDate:aTimeInterval];
    return newDate;
}

Suggestion :

- (NSDate *) dateByAddingDays: (NSInteger) dDays
{
    NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
    [dateComponents setDay:dDays];
    NSDate *newDate = [[NSCalendar currentCalendar] dateByAddingComponents:dateComponents toDate:self options:0];
    return newDate;
}

If you can give any suggestions that would be awesome.

At the time of writing, the date is 18th of July 2014, I am checking to see if the 17th of July is last week. It isn't last week, but isLastWeek is returning YES. I believe it might just be a missing ! before [self isSameWeekAsDate:newDate]; in isLastWeek.

In TimeFormatters line 96

NSString *LocStr(NSString *const key) {

I'm getting the below warning

Warning: No previous prototype for function 'LocStr'

(lldb) po [NSDate date]
(id) $2 = 0x1513c0c0 2012-08-23 22:00:00 +0000

(lldb) po [[NSDate date] dateBySubtractingMinutes:1]
(id) $1 = 0x0a19b6f0 2148-09-30 04:27:16 +0000

This is the method

- (NSDate *) dateByAddingMinutes: (NSUInteger) dMinutes
{
    NSTimeInterval aTimeInterval = [self timeIntervalSinceReferenceDate] + D_MINUTE * dMinutes;
    NSDate *newDate = [NSDate dateWithTimeIntervalSinceReferenceDate:aTimeInterval];
    return newDate;         
}

- (NSDate *) dateBySubtractingMinutes: (NSUInteger) dMinutes
{
    return [self dateByAddingMinutes: (dMinutes * -1)];
}

(line 130)

• (BOOL) isThisYear
  {
  return [self isSameWeekAsDate:[NSDate date]];
  }

Somehow, that manages to work in some weird cases

Anyhow I think I fixed it, the right code should be

• (BOOL) isThisYear
  {
  return [self isSameYearAsDate:[NSDate date]];
  }

Hi Erica,

/*
Erica Sadun, http://ericasadun.com
iPhone Developer's Cookbook 3.x and beyond
BSD License, Use at your own risk
*/

Which BSD license (e.g. 4-clause, 3-clause, or 2-clause)?

thanks.

When using these extensions I found that adding the date returned was incorrect when the value returned was within a DST time change.

This can be fixed by using date components for all the add/subtract methods.

Here's a blog post I found that describes this issue.

It's pretty easy, but would be a handy addition

In the current implementation:

- (BOOL) isThisYear
{
        return [self isSameWeekAsDate:[NSDate date]];
}

This is wrong of course. Should be:

- (BOOL) isThisYear
{
    return [self isSameYearAsDate:[NSDate date]];
}

TimeFormatters.m, line 173
Warning: "Method possibly missing a [super dealloc] call"

It's really bad to add/subtract dates like you are you you don't account for any of the issues around dates. You should be using the calendrical operations instead of just adding 86400 seconds per day. Watch the WWDC video on this and he clearly explains why what you're doing is unsafe.

Hi Erica,

First of all, this category is awesome. Could you post a new podspec that points at the most recent commits?

In the method - (NSDate *) dateAtEndOfDay it is assumed that there are 11 hours in a day which is wrong. Method implementation should be something like:

- (NSDate *) dateAtEndOfDay
{
  NSDateComponents *components = [[NSDate currentCalendar] components:componentFlags fromDate:self];
  components.hour = 23;
  components.minute = 59;
  components.second = 59;
  return [[NSDate currentCalendar] dateFromComponents:components];
}

Using an NSUInteger for the

• (NSDate *) dateByAddingDays: (NSUInteger) dDays

does not permit proper calculations when subtracting days, which is called by this method:

• (NSDate *) dateBySubtractingDays: (NSUInteger) dDays

"source": {
"git": "https://github.com/erica/NSDate-Extensions.git",
"commit": "7c6730b8e5e4740a332d839f3597bcce11d83160"
},
Could you please update one version for CocoaPods

I've just found that all date calculations happens with timezone specified in current calendar e.g. [NSCalendar currentCalendar]. But when you are working with time in different timezones, it become more or less useless.

It would be great if you could set the timezone for calendar. Something like that:
[CURRENT_CALENDAR setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];

Thanks!

Can you add a Package.swift and tag that commit with a version number so this can be easily used with SPM?

The pod 'NSDate-Extensions' version is not the latest one, could you please update it?

I think if this method doesn't work properly or his name is wrong.
As a consequence, methods like isNextWeek too.

isSameMonthsAsDate and isSameYearAsDate compare months with years, but method isSameWeekAsDate dimensions interval between two days.

Maybe my solution does that we need. it compares if date has same week like other date.

- (BOOL) isSameWeekAsDate: (NSDate *) aDate
{
    NSDate *startWeek = [self dateAtStartOfWeek];

    NSInteger timeInterval = [aDate timeIntervalSinceDate:startWeek];
    return (timeInterval > 0 && timeInterval < D_WEEK);
}

- (NSDate *) dateAtStartOfWeek
{
    // Get the weekday component of the current date
    NSDateComponents *weekdayComponents = [[NSDate currentCalendar] components:NSWeekdayCalendarUnit
                                                                      fromDate:self];
    NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
    // required having 7 days in one week
    [componentsToSubtract setDay: 0 - ((([weekdayComponents weekday] - [[NSDate currentCalendar] firstWeekday]) + 7 ) % 7)];

    NSDate *beginningOfWeek = [[NSDate currentCalendar] dateByAddingComponents:componentsToSubtract
                                                                        toDate:self options:0];
// optional
    NSDateComponents *components = [[NSDate currentCalendar] components: componentFlags
                                                               fromDate: beginningOfWeek];
    beginningOfWeek = [[NSDate currentCalendar] dateFromComponents: components];

    return [beginningOfWeek dateAtStartOfDay];
}

Would be nice. Thanks

SDK IOS7.1 Above Versions

• (NSInteger) week
  {
  NSDateComponents *components = [[NSDate currentCalendar] components:componentFlags fromDate:self];
  return components.week;
  }

Should be replaced

• (NSInteger) week
  {
  NSDateComponents *components = [[NSDate currentCalendar] components:componentFlags fromDate:self];
  return components.weekOfYear;
  }

Precautions:
componentFlags add "NSWeekOfYearCalendarUnit"

• (NSInteger)week NS_CALENDAR_DEPRECATED(10_4, 10_9, 2_0, 7_0, "Use weekOfMonth or weekOfYear, depending on which you mean");

ios7 above can not be used

• (NSInteger)week
  {
  NSDateComponents *components = [[NSDate currentCalendar] components:componentFlags fromDate:self];

  return components.week;
  }

They should both have return [self isSameWeekAsDate:newDate]; instead of return [self isSameYearAsDate:newDate];

can't imagine why?

dateByAddingDays takes a NSUInteger but gets called with a negative number from dateBySubtractingDays: this causes incorrect result. Haven't had time to look around but this bug may not be limited to just dateByAddingDays.

Hi Erica,

I'm sure you've heard about the CocoaPods project, maybe you're using it yourself already?! It would be really nice, if you could start creating git tags on your great NSDate-Exentions repository. The reason behind this request is the section "Unversioned libraries":

http://docs.cocoapods.org/guides/contributing_to_the_master_repo.html

Thanks,
plu