您可以将字符串 Date 转换为 Date/NSDate ，如下代码:-

You can convert String Date into Date/NSDate like below code: -

Swift 3.2 & Swift 4.2

Swift 3.2 & Swift 4.2

日期字符串

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd-MM-yyyy" //Your date format
dateFormatter.timeZone = TimeZone(abbreviation: "GMT+0:00") //Current time zone
//according to date format your date string
guard let date = dateFormatter.date(from: "01-01-2017") else {
    fatalError()
}
print(date) //Convert String to Date

日期为字符串

dateFormatter.dateFormat = "MMM d, yyyy" //Your New Date format as per requirement change it own
let newDate = dateFormatter.string(from: date) //pass Date here
print(newDate) //New formatted Date string

输出:-

2017-01-11 00:07:00 +0000
Jan 11, 2017