如果让 ISO8601DateFormatter 来自 String

Question

我的回复是 returns 对象的日期，有时 returns 年份，有时 returns ISO8601DateFormatter 样式的日期 (1995-01-01T00: 00:00Z)

问题是我怎样才能得到一个 if let 来识别何时值是字符串形式的年份或字符串中的 ISO8601Date。

Answer 1

我最终这样做了：

      let pulledDate = "1995-01-01T00:00:00Z"
      let dateFormatter = ISO8601DateFormatter()
      dateFormatter.formatOptions = [.withYear, .withMonth, .withDay, .withTime, .withDashSeparatorInDate, .withColonSeparatorInTime]

      if let date = dateFormatter.date(from: pulledDate ?? ""){
          let units: Set<Calendar.Component> = [.year]
          let comps = Calendar.current.dateComponents(units, from: date)
          print("It is a date year = \(comps.year)")
      }
      else{
          print("It is not a date")
      }

如果让 ISO8601DateFormatter 来自 String

if let ISO8601DateFormatter from String

swift3

swift4