Date Formatting Returns Nil [duplicate]

问题

This question already has answers here:

I get nil when using NSDateFormatter in swift (2 answers)

Closed 4 years ago.

I'm getting nil when trying to create a date from a string. What am I doing wrong?

let createdAt = passesDictionary["createdAt"] as? String
print(createdAt)
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let createdDate = dateFormatter.dateFromString(createdAt!)
print(createdDate)

createdAt is Optional("2016-05-03T19:17:00.434Z"), but createdDate is nil.

回答1:

The date string "2016-05-03T19:17:00.434Z" does match the pattern you gate to NSDateFormatter ("yyyy-MM-dd"). Try this pattern: yyyy-MM-dd'T'HH:mm:ss.SSSZ.

Here's a table of the tokens you can use in the dateFormat, as linked from the Apple documentation.

来源：https://stackoverflow.com/questions/37122158/date-formatting-returns-nil