wrong date

Can you explain where you see an error : what did you expect ? What did you get ?

I tested in playGround, seems OK.

When you use

let dateFormatter = DateFormatter(dateFormat: "HH:mm")

let myDate = dateFormatter.date(from: "10:30")

then only hh:mm are used, and date is set by default to 2000-01-01

The code you’ve posted in problematic in many ways, and it’s hard to say which of those problems is the one you’re investigating and which of them are just your test code. For example, this code:

extension DateFormatter {
    convenience init(dateFormat: String) {
        self.init()
        self.locale = Locale.current
        self.timeZone = TimeZone.current
        self.dateFormat =  dateFormat
    }
}

let dateFormatter = DateFormatter(dateFormat: "HH:mm")

is problematic because it’s using a fixed-format date string to set up a date formatter that’s obviously intended to be used for localised dates (based on your setting of the

locale

property). When you try to mix fixed-format date strings and localised date you inevitably run into problems (QA1480 NSDateFormatter and Internet Dates explains one of the potential gotchas here, but there are many more).

So, can you explain more about what you’re trying to achieve here?

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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Hi,

sure,the date and time is wrong (see print timestamp)

i want to get a new date only the HH.mm is given and (add with Int(min))

(get only HH:mm) as initial Value.

for example time is 10:30 AM (add 45min)

expected the correct Date is as Year and month,(10:30 + 45 min) is 2018-10-18 11:15 AM

why is the date 2000 ???? as you can see the current Timestamp is correct.

If you want to set the hour of today, could use:

let otherDate = Calendar.current.date(bySettingHour: 10, minute: 30, second: 0, of: Date())!
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd hh:mm"
dateFormatter.timeZone = TimeZone(abbreviation: "UTC+2")     // select your time zone
let str = dateFormatter.string(from: otherDate)

I think I see what you’re getting at here.

The problem is that

Date

represents a fixed point in time, so if you ask

DateFormatter

to parse a string that only contains time components, it has to come up with some default values for the date. It does this using the

defaultDate

property. By default this is

nil

, which is treated like the start of the year 2000 UTC. Hence a date formatter with no date components will default to 1 Jan 2000.

let df = DateFormatter()
df.locale = Locale(identifier: "en_US_POSIX")
df.timeZone = TimeZone(secondsFromGMT: 0)
df.dateFormat = "HH':'mm"
print(df.date(from: "12:34")!)  // prints "2000-01-01 12:34:00 +0000"

IMPORTANT Using a value of

nil

for

defaultDate

is not the same as using

Date(timeIntervalSinceReferenceDate: 0.0)

. The reference date used by

Date

is the start of the year 2001. I’m sure there’s a good reason for this mismatch (-:

If you want the date formatter to default to some other date, just set the

defaultDate

parameter.

df.defaultDate = Date(timeIntervalSinceReferenceDate: 561816000.0)  // 2018-10-21 12:00:00 UTC
print(df.date(from: "12:34")!)  // prints "2018-10-21 12:34:00 +0000"

WARNING In this example I’m force unwrapping the resulting date. That’s safe because every time is valid for every date in UTC. This is not true for all time zones, and that can cause problems on days where daylight savings time ‘springs forward’. For example:

let df = DateFormatter()
df.locale = Locale(identifier: "en_US_POSIX")
df.timeZone = TimeZone(identifier: "Europe/London")
df.dateFormat = "HH':'mm"

df.defaultDate = Date(timeIntervalSinceReferenceDate: 543672000.0)  // 2018-03-25 12:00:00 UTC
print(df.date(from: "01:30"))  // prints nil

This is because the UK transitioned from GMT to BST on 25 Mar 2018, hence 01:30 does not exist on that day.

Beyond that, there are still problems associated with the locale. So far you’ve not clarified whether you’re working with fixed-format dates or localised dates. If it’s the former then hard coding

en_US_POSIX

is the right solution; if it’s the latter, things get more complex.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"