Timezone issue with UIDatePicker Date: 1 Hour Wrong

Question

I'm having an issue with the Monotouch UIDatePicker being 1 hour behind. I think this is to do with Time Zones or something similar. I've tried explicitly setting the TimeZone and Locale of my UIDatePicker but this doesn't seem to be helping.

datePicker.Locale = NSLocale.CurrentLocale;
datePicker.TimeZone = NSTimeZone.LocalTimeZone;

In the ValueChanged handler the following line returns a value 1 hour earlier than the time selected in the user interface:

var date = DateTime.SpecifyKind((s as UIDatePicker).Date, DateTimeKind.Local).ToLocalTime();

In the ValueChanged Handler I've double checked that the Locale and TimeZone is the same as what was set. The TimeZone is Europe/Dublin and Locale en_US. This information was retrieved by:

datePicker.Locale.LocaleIdentifier;
datePicker.DatePicker.TimeZone;

Is there another step I'm missing?

Thanks!

Is it possible that daylight savings is in effect? This can sometimes cause hour differences similar to what you seem to be experiencing. — Melvin DVaz, Sep 10 '13 at 10:23

score 12 · Accepted Answer · edited May 23 '17 at 12:25

12

The date returned from DatePicker is in UTC format. There are several methods of converting UTC to local time. As this answer states ToLocalTime is the best one.

DateTime.SpecifyKind(datePicker.Date, DateTimeKind.Utc).ToLocalTime();

edited May 23 '17 at 12:25

Community

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answered Sep 13 '13 at 02:59

Daria Trainor

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I think this is the correct answer. In the original code, the OP specified `DateTimeKind.Local` instead of `DateTimeKind.Utc`. Since an `NSDate` represents UTC but the conversion doesn't set the `.Kind`, this is how you have to do it. – Matt Johnson-Pint Sep 16 '13 at 07:14
But datePicker.Date is an NSDate and the first parameter of the method DateTime.SpecifyKind is a DateTime... – leoneboaventura May 22 '15 at 10:52

score 2 · Answer 2 · answered Sep 10 '13 at 15:31

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After var date = DateTime ..., add the following:

if (date.IsDaylightSavingTime ())
    date = date.AddHours (1);

answered Sep 10 '13 at 15:31

frogge

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Daylight savings time is not always adjusted by an hour. http://www.timeanddate.com/time/dst/ http://infiniteundo.com/post/25509354022/more-falsehoods-programmers-believe-about-time-wisdom – Daria Trainor Sep 12 '13 at 02:37
Indeed. It's a quick fix. I'd rather be almost correct than completely wrong, so to speak. You could of course use a DST offset based on timezone. Do you have a nice proposal for this? I like the second link, but it doesn't give any answers; only states that we carry misconceptions. – frogge Sep 12 '13 at 07:58
The answer is in my answer below. Use DateFormatter, it takes care of DST for you. – Daria Trainor Sep 13 '13 at 02:39
Yes, but only when outputting as text – frogge Sep 13 '13 at 07:20
TimeZoneInfo.ConvertTimeFromUtc returns DateTime. – Daria Trainor Sep 14 '13 at 09:04

score 2 · Answer 3 · answered Sep 12 '13 at 08:42

This magical code fixed all my problems with daylight savings and timezones. Write if you need help.

NSDate sourceDate = date;

NSTimeZone sourceTimeZone = new NSTimeZone ("UTC");
NSTimeZone destinationTimeZone = NSTimeZone.LocalTimeZone;

int sourceGMTOffset = sourceTimeZone.SecondsFromGMT (sourceDate);
int destinationGMTOffset = destinationTimeZone.SecondsFromGMT (sourceDate);
int interval = destinationGMTOffset - sourceGMTOffset;

var destinationDate = sourceDate.AddSeconds (interval);

var dateTime = new DateTime(2001, 1, 1, 0, 0,0).AddSeconds(destinationDate.SecondsSinceReferenceDate);

DescriptionLabel.Text = dateTime.ToString ("dd.MM.yyyy. HH:mm");
this.date = destinationDate;

This code adds unnecessary complexity. If you want to convert time to your local timezone simply use DateTime.ToLocalTime(). — Daria Trainor, Sep 16 '13 at 02:36

Timezone issue with UIDatePicker Date: 1 Hour Wrong

3 Answers3