Why date formatter crashes?

Question

My below code is working fine. I don't know why it crashes sometimes(Mostly on application launch. 1 case out of ~100).

extension Formatter {
    static let enUSPOSIX: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")//
        return formatter
    }()
}


let dateFormatter = Formatter.enUSPOSIX
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss+hh:mm"
let date = dateFormatter.date(from: "2018-05-13T00:00:00+05:30")
dateFormatter.timeZone = TimeZone(identifier: "UTC")
let calendar = Calendar.current
let dayComponent = calendar.component(.year, from: date!)//crashes here sometime
print(dayComponent)

I recommend to look up https://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns. `+hh:mm` is *not* the correct pattern for a time zone. — Martin R, Sep 05 '18 at 06:27
@MartinR: Nice catch, but can you please explain why it only crash sometimes, not all of times. — Quoc Nguyen, Sep 05 '18 at 06:31
@QuocNguyen: Actually the provided example does *not* crash in my test, because `+05:30` matches `+hh:mm` (05 happens to be a valid hour in the 1-12 hour format). It would for example crash for `-05:30` or `+13:00` because these do not match the pattern. — Martin R, Sep 05 '18 at 06:37
@MartinR thanks for explain. The priovided example doesn't not crash in my test, too :D — Quoc Nguyen, Sep 05 '18 at 06:41
@MartinR thanks. is `TimeZone(identifier` should be `TimeZone(abbreviation` ? — amey rane, Sep 05 '18 at 06:45
@MartinR when i use `"yyyy-MM-dd'T'HH:mm:ssZZZZZ"` it crashes(somtimes) please help :( — amey rane, Sep 06 '18 at 07:47

vadian · Answer 1 · 2018-09-06T08:20:37.643

1

Basically your date format is wrong. The time zone +05:30 is ZZZZZ not +hh:mm, please read unicode.org Date Format Patterns

 dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"

Edit:

For this standard ISO8601 format I'd prefer ISO8601DateFormatter

let dateFormatter = ISO8601DateFormatter()
let date = dateFormatter.date(from: "2018-05-13T00:00:00+05:30")

edited Sep 06 '18 at 08:20

answered Sep 05 '18 at 06:30

vadian

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Sorry please explain how to decide `ZZZZZ` ? – amey rane Sep 05 '18 at 06:38
@ameyrane From the mentioned documentation: *The ISO8601 extended format with hours, minutes and optional seconds fields. The ISO8601 UTC indicator "Z" is used when local time offset is 0* – vadian Sep 05 '18 at 06:40
@Rob i think `+0530` is for `X` not `+05:30` ? – amey rane Sep 05 '18 at 06:49
When i use `"yyyy-MM-dd'T'HH:mm:ssZZZZZ"` it crashes(somtimes) please help :( – amey rane Sep 06 '18 at 07:48
What dates do crash? – vadian Sep 06 '18 at 08:16
`"2018-09-13T00:00:00+05:30"` @vadian – amey rane Sep 06 '18 at 08:20

Kamil Harasimowicz · Answer 2 · 2018-11-21T14:28:50.590

Today I met exactly the same problem. Application randomly crashes on production because of force unwrapping on open func date(from string: String) -> Date?

My code looked like this:

let creationDate: Date = {
    let dateFormatter = DateFormatter()
    return dateFormatter.date(from: "19-06-2018 14:00")!
}()

After my investigation I realized that crashes appear only on devices which have set 12h date format in device settings. In these cases 14:00 does not exist because it should be "2:00PM".

Simply change in code fix that problem:

let creationDate: Date = {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "dd-MM-yyyy HH:mm"
    dateFormatter.locale = Locale(identifier: "en_US_POSIX")

    return dateFormatter.date(from: "19-06-2018 14:00")!
}()

score 0 · Answer 3 · answered Sep 11 '18 at 10:34

I had the same issue when testing on one of my applications

let dateFormatter = Formatter.enUSPOSIX
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss+hh:mm"
let date = dateFormatter.date(from: "2018-05-13T00:00:00+05:30")
dateFormatter.timeZone = TimeZone(identifier: "UTC")
let calendar = Calendar.current
let dayComponent = calendar.component(.year, from: date!)

This is Crashing because the date object is nil so when fore unwrapping the date in dayComponent line this crashes. try this

let dateFormatter = Formatter.enUSPOSIX
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss+hh:mm"
if let date = dateFormatter.date(from: "2018-05-13T00:00:00+05:30"){
   dateFormatter.timeZone = TimeZone(identifier: "UTC")
   let calendar = Calendar.current
   let dayComponent = calendar.component(.year, from: date!)
}else{
  dateFormatter.dateFormat = "yyyy-MM-dd'T'hh:mm:ss+hh:mm" // Date as 12 hour  
 if let date = dateFormatter.date(from: "2018-05-13T00:00:00+05:30"){
   dateFormatter.timeZone = TimeZone(identifier: "UTC")
  let calendar = Calendar.current
  let dayComponent = calendar.component(.year, from: date!)
} else{
   print("Cannot format Date")
 }
}

Why date formatter crashes?

3 Answers3

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