Get Date Parts from a NSDate value

Question

Hello,

I'm using a UIDatePicker and I'm having problems with converting this data to a System.DateTime value in MonoTouch. There are problems with conversions from NSDate to DateTime, which I've mostly solved, but now I see that if you choose a date that is NOT in the same Daylight Savings Time period then you are an hour off. For example, if I pick a date in January 2010 I'll have an offset issue.

What I'd like to do is when a user selects a date/time from the UIDatePicker is to get the Year, Month, Day, Hour, and Minute values of the NSDate and just create a New System.DateTime with those values and I'll always be assured to get a date value exactly as the user see's it in the UIDatePicker.

How can I break down a NSDate value into the various date parts?

Thank you.

Answer 1

It appears this can be done using an instance of NSDateComponents. The following has been copied from Date Components and Calendar Units:

To decompose a date into constituent components, you use the NSCalendar method components:fromDate:. In addition to the date itself, you need to specify the components to be returned in the NSDateComponents object. For this, the method takes a bit mask composed of Calendar Units constants. There is no need to specify any more components than those in which you are interested. Listing 3 shows how to calculate today’s day and weekday.

Listing 3 Getting a date’s components

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc]  initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents = [gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:today];
NSInteger day = [weekdayComponents day];
NSInteger weekday = [weekdayComponents weekday];