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Published 20 hours ago • verified publisher icon Kotlin

Add LocalDate to NSDate and LocalDateTime to NSDate conversions

Open 4brunu opened this issue 3 years ago • 2 comments

In iOS is much more convenient to work with NSDate than with NSDateComponents. But currently there is no direct converters from LocalDate/LocalDateTime to NSDate. This PR fixes that.

4brunu avatar Feb 17 '22 22:02 4brunu

Hey @dkhalanskyjb, Any news on this? Is there any more required changes to merge this PR? Thanks 👍

4brunu avatar Mar 07 '22 19:03 4brunu

Hi!

  1. Regarding public fun LocalDateTime.toNSDate(): NSDate? {, we do suppose that nil is not possible, but if we are wrong, this will lead to crashes in edge cases. This needs testing.

  2. NSDateComponents is just a bag of values, the conversion is pretty straightforward. NSDate, on the other hand, is a specific moment in time, the conversion is easy to get wrong. For example, I remember seeing issues with how years < 0 were treated in Darwin, and also, there's a difference between the ISO-8601 calendar we use and the Gregorian calendar which may be passed as an argument, so the wrong results may arise much closer to our time, in year 1582. This should be thoroughly checked and (I'm sure some problems will arise) fixed.

  3. The behavior of LocalDate.toNSDate needs to be clarified. What does it do, exactly? A function with a similar signature in our library is LocalDate.atStartOfDayIn(timeZone: TimeZone): Instant. The function is tricky, as it needs to account for DST transitions, due to which a day sometimes starts at 01:00 (or, possibly, some other time), not at 00:00. Does the conversion by the Foundation library do the same? If so, this needs to be documented, and the name should probably be changed as well.

  4. It feels logical to have an inverse conversion then: NSDate.toKotlinLocalDateTime.

dkhalanskyjb avatar Mar 09 '22 08:03 dkhalanskyjb

Closing due to inactivity and a lack of interest from our users. We can always create a new PR if there's a demand.

dkhalanskyjb avatar Nov 29 '23 13:11 dkhalanskyjb

a note: just last week I was writing my own converter. fyi: my first attempt ended up with a timezone bug.

use case: I needed localized formatting of my local date.

hrach avatar Nov 29 '23 20:11 hrach

I also need this, I just gave up on this because I don't have the time to do this with all the suggestions made

4brunu avatar Nov 29 '23 21:11 4brunu

Ok, I filed an issue: https://github.com/Kotlin/kotlinx-datetime/issues/322 Please feel free to share any information.

dkhalanskyjb avatar Nov 30 '23 14:11 dkhalanskyjb