无法将 date/time 字符串转换为日期

Can't convert date/time string into date

从字符串到日期的转换一直返回 nil:

if let dateString = dict["dateScanned"] as? String {
       let strTime = dateString // 9/5/2017 12:00:00 AM
       let formatter = DateFormatter()
       formatter.dateFormat = "MM/dd/yyyy HH:mm:ss"
       let myDate = formatter.date(from: strTime)  // myDate = nil
       print(myDate)
   }

您缺少 AM/PM 信息:

formatter.dateFormat = "MM/dd/yyyy hh:mm:ss a"

(而且你必须使用小写 hh,正如 vadian 所指出的)