How to show year only in NSDatePicker - objective-c

Question

I want to show year component only in a NSDatePicker.
I tried set/add NSDateFormatter to NSDatePicker, but with no luck. (By dragging a NSDateFormatter to NSDatePicker in nib)
Is there any way to achieve this without subclassing NSDatePicker or NSTextField? Thank you!

Answer 1

After diving into Apple's Documentation, I found the solution and want to post it here, in case it is useful for someone else.
No need to subclass NSDatePicker, there is a method - (void)setDatePickerElements:(NSDatePickerElementFlags)elementFlags which specifies which element the date picker would display. elementFlags is a constant, defined by a enum as:
enum {
NSHourMinuteDatePickerElementFlag = 0x000c,
NSHourMinuteSecondDatePickerElementFlag = 0x000e,
NSTimeZoneDatePickerElementFlag = 0x0010,
NSYearMonthDatePickerElementFlag = 0x00c0,
NSYearMonthDayDatePickerElementFlag = 0x00e0,
NSEraDatePickerElementFlag = 0x0100,
};
typedef NSUInteger NSDatePickerElementFlags;
When looking at those constants, I find it is just a bit mask. Bit place and the corresponding calendar elements is as follows:
15 - 9 bit: Unknown. Maybe unused.
8 bit: Era. (Would not display anything if has a 4-digit year format.)
7 bit: Year.
6 bit: Month.
5 bit: Day.
4 bit: Time zone.
3 bit: Hour.
2 bit: Minute.
1 bit: second.
0 bit: Unknown. Maybe millisecond, or unused.
So, the following line would give me a year only date picker:
[_yearOnlyDatePicker setDatePickerElements:0x0080];
_yearOnlyPicker is an instance of NSDatePicker.
Here is the result:
How yearOnlyDatePicker looks like in Interface Builder:
How yearOnlyDatePicker looks like when running the app:

Answer 2

-[NSDatePicker setDatePickerElements:] can no longer be tricked into showing year only.
A year-only NSDatePicker can be obtained by configuring a year-month picker and subclassing NSDatePickerCell to prevent it from creating the month and separator fields:
- (void)_addSubfieldForElement:(int)arg1 withDateFormat:(id)arg2 referenceStrings:(id)arg3
{
if ((arg1 == 6) || (arg1 == 100)) {
return;
}
[super _addSubfieldForElement:arg1 withDateFormat:arg2 referenceStrings:arg3]; // Private API
}
Please file bug reports with Apple to request a year-only variant of NSDatePicker. I also requested a week-of-year picker.

Answer 3

It is easy you don't need to use NSDatePicker. All you have to do is create a range of years you want and use it as datasource for normal picker.
for (int i=1900; i<=currentYear; i++) {
[_yourDataSourceArr addObject:[NSString stringWithFormat:#"%d",i]];
}