把它放在扩展中，并像下面这样调用它。它很容易在整个应用程序中使用。

self.getFormattedDate(strDate: "20-March-2019", currentFomat: "dd-MMM-yyyy", expectedFromat: "yyyy-MM-dd")

实现

func getFormattedDate(strDate: String , currentFomat:String, expectedFromat: String) -> String{
    let dateFormatterGet = DateFormatter()
    dateFormatterGet.dateFormat = currentFomat

    let date : Date = dateFormatterGet.date(from: strDate) ?? Date()

    dateFormatterGet.dateFormat = expectedFromat
    return dateFormatterGet.string(from: date)
}

这是一个完整的日期格式的swift扩展

extension Date {
   func getFormattedDate(format: String) -> String {
        let dateformat = DateFormatter()
        dateformat.dateFormat = format
        return dateformat.string(from: self)
    }
    
    func getFormattedDate(style: DateFormatter.Style) -> String {
         let dateformat = DateFormatter()
         dateformat.dateStyle = style
         return dateformat.string(from: self)
     }
}

使用

myDate.getFormattedDate(style: .medium) //medium, short, full, long

OR

myDate.getFormattedDate(format: "yyyy/MM/dd HH:mm:ss")

斯威夫特3

func dataFormat(dataJ: Double) -> String {

        let dateFormatter = DateFormatter()
        dateFormatter.dateStyle = .long
        dateFormatter.timeStyle = .none
        let date = Date(timeIntervalSince1970: dataJ)
        return (dataJ != nil) ? "Today, \(dateFormatter.string(from: date))" : "Date Invalid"

    }

我解决了我的问题格式yyyy-MM-dd' t ' hh:mm:ss.SSS' z '(e。g 2018-06-15T00:00:00.000Z)

func formatDate(date: String) -> String {
   let dateFormatterGet = DateFormatter()
   dateFormatterGet.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"

   let dateFormatter = DateFormatter()
   dateFormatter.dateStyle = .medium
   dateFormatter.timeStyle = .none
   //    dateFormatter.locale = Locale(identifier: "en_US") //uncomment if you don't want to get the system default format.

   let dateObj: Date? = dateFormatterGet.date(from: date)

   return dateFormatter.string(from: dateObj!)
}

要将2016-02-29 12:24:26转换为日期，使用以下日期格式化程序:

let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd hh:mm:ss"

编辑:获取输出2016年2月29日使用这个日期格式化器:

let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "MMM dd, yyyy"

将@BatyrCan转换为Swift 5.3的额外格式。在Xcode 12中测试。

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm:ss"
var dateFromStr = dateFormatter.date(from: "12:16:45")!

dateFormatter.dateFormat = "hh:mm:ss a 'on' MMMM dd, yyyy"
//Output: 12:16:45 PM on January 01, 2000

dateFormatter.dateFormat = "E, d MMM yyyy HH:mm:ss Z"
//Output: Sat, 1 Jan 2000 12:16:45 +0600

dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
//Output: 2000-01-01T12:16:45+0600

dateFormatter.dateFormat = "EEEE, MMM d, yyyy"
//Output: Saturday, Jan 1, 2000

dateFormatter.dateFormat = "MM-dd-yyyy HH:mm"
//Output: 01-01-2000 12:16

dateFormatter.dateFormat = "MMM d, h:mm a"
//Output: Jan 1, 12:16 PM

dateFormatter.dateFormat = "HH:mm:ss.SSS"
//Output: 12:16:45.000

dateFormatter.dateFormat = "MMM d, yyyy"
//Output: Jan 1, 2000

dateFormatter.dateFormat = "MM/dd/yyyy"
//Output: 01/01/2000

dateFormatter.dateFormat = "hh:mm:ss a"
//Output: 12:16:45 PM

dateFormatter.dateFormat = "MMMM yyyy"
//Output: January 2000

dateFormatter.dateFormat = "dd.MM.yy"
//Output: 01.01.00

//Customisable AP/PM symbols
dateFormatter.amSymbol = "am"
dateFormatter.pmSymbol = "Pm"
dateFormatter.dateFormat = "a"
//Output: Pm

// Usage
var timeFromDate = dateFormatter.string(from: dateFromStr)
print(timeFromDate)