Swift - iOS - 将字符串转换为日期并发出

Question

I have an extension on String to convert my date strings to a Date type in Swift 5.2

extension String {
  func toDate(withFormat format: String = "MMM d, YYYY HH:mm:ss a") -> Date {
    let dateFormatter = DateFormatter()
    dateFormatter.locale = Locale(identifier: "en_US")
    dateFormatter.calendar = Calendar(identifier:  .iso8601)
    dateFormatter.timeZone = .current
    dateFormatter.dateFormat = format
    guard let date = dateFormatter.date(from: self) else {
      preconditionFailure("Check the format!!!")
    }
    return date
  }
}

when I try this to convert my date_string is always wrong(check below) :

var sampleDate = "May 5, 2021 1:34:15 AM"
let newDate = sampleDate.toDate()
print(newDate) //prints: "2020-12-28 05:34:15 +0000\n"

My date_string that I want to convert is always in a similar format: "May 5, 2020 9:20 5:39:15 PM"

Any idea what could be wrong? I played around with local, calendar, timezone but did not work! I'm in the US East Coast timezone right now.

Thanks, Cam

Answer 1

Your DateFormatter's dateFormat should be "MMM d, yyyy hh:mm:ss a"

("yyyy" instead of "YYYY" and "hh" instead of "HH")

That works.

Edit:

Or, as Leo pointed out in the comments, "MMM d, yyyy h:mm:ss a" (With only one h ) would be better, and it's safer to use

dateFormatter.locale = Locale(identifier: "en_US_POSIX")

(That tells the date formatter not to try to adjust the date format for different local date formatting conventions.)