我无法将 iso8601 转换为字符串 swift

Question

I have a string coming from API and its format will be like this

"2021-03-01T15:00:00+07:00"

so i try to convert this string to date using this code

   // string to date
   let dateFormatter = DateFormatter()
   dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
   let date = dateFormatter.date(from: isoDate)!
   
   print("date from date Formatter = \(date)")
   
   // convert date back to string
   dateFormatter.dateFormat = "EEEE HH:mm"
   let dateString = dateFormatter.string(from: date)
   
   print("date string \(dateString)")
   return dateString    

The result that I expect is -> "2021-03-01 08:00:00 +0000" , "Monday 15:00"

When I try this on playground the result is what I want, but when I try this on my project the result is

-> "1478-03-01 08:00:00 +0000" , "Sunday 14:42"

How can I change the result to the same as i expect? Thanks

Answer 1

It looks like you are using a different calendar than you expect in your project ( buddhist maybe?) and I guess this is because you haven't set one explicitly so it's the one set in System Preferences.

So if you for some reason do not want to use the users current calendar (and locale and time zone) you need to set those properties on your date formatter instance

//Gregorian calendar
dateFormatter.calendar = Calendar.init(identifier: .gregorian)
//UTC time zone
dateFormatter.timeZone = TimeZone(identifier: "UTC")
//English locale
dateFormatter.locale = Locale(identifier: "en_US_POSIX")

This will give you the expected output.

Note that the playground is a bit inconsequent in what it uses and it seems to be a mix of what we have set in our System preferences and hardcoded values.