您可以为此使用扩展。

extension NSDate {
    //NSString to NSDate
    convenience
    init(dateString:String) {
        let nsDateFormatter = NSDateFormatter()
        nsDateFormatter.dateFormat = "yyyy-MM-dd hh:mm:ss"
        // Add the locale if required here
        let dateObj = nsDateFormatter.dateFromString(dateString)
        self.init(timeInterval:0, sinceDate:dateObj!)
    }

    //NSDate to time string
    func getTime() -> String {
        let timeFormatter = NSDateFormatter()
        timeFormatter.dateFormat = "hh:mm"
        //Can also set the default styles for date or time using .timeStyle or .dateStyle
        return timeFormatter.stringFromDate(self)
    }

    //NSDate to date string
    func getDate() -> String {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "dd, MMM"
        return dateFormatter.stringFromDate(self)
    }

    //NSDate to String
    func getString() -> String {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd hh:mm:ss"
        return dateFormatter.stringFromDate(self)
    }
}

因此，在执行时，实际代码将如下所示

    var dateObjFromString = NSDate(dateString: cutDateTime)
    var dateString = dateObjFromString.getDate()
    var timeString = dateObjFromString.getTime()
    var stringFromDate = dateObjFromString.getString()

也有一些默认方法，但我猜它可能不适用于您从文档中给出的格式

    -dateFromString(_:)
    -stringFromDate(_:)
    -localizedStringFromDate(_ date: NSDate,
                     dateStyle dateStyle: NSDateFormatterStyle,
                     timeStyle timeStyle: NSDateFormatterStyle) -> String

Swift 4及后续版本

更新:2018

字符串到日期

var dateString = "02-03-2017"
var dateFormatter = DateFormatter()

// This is important - we set our input date format to match our input string
// if the format doesn't match you'll get nil from your string, so be careful
dateFormatter.dateFormat = "dd-MM-yyyy"

//`date(from:)` returns an optional so make sure you unwrap when using. 
var dateFromString: Date? = dateFormatter.date(from: dateString)

日期到字符串

var formatter = DateFormatter()
formatter.dateFormat = "dd-MM-yyyy"
guard let unwrappedDate = dateFromString else { return }

//Using the dateFromString variable from before. 
let stringDate: String = formatter.string(from: dateFromString)

斯威夫特3

更新:2017年7月20日

NSDate的字符串

var dateString = "02-03-2017"
var dateFormatter = DateFormatter()
// This is important - we set our input date format to match our input string
// if the format doesn't match you'll get nil from your string, so be careful
dateFormatter.dateFormat = "dd-MM-yyyy"
var dateFromString = dateFormatter.date(from: dateString)

NSDate到字符串

var formatter = DateFormatter()
formatter.dateFormat = "dd-MM-yyyy"
let stringDate: String = formatter.string(from: dateFromString)

斯威夫特

更新:2015年10月22日

NSDate的字符串

var dateString = "01-02-2010"
var dateFormatter = NSDateFormatter()
// this is imporant - we set our input date format to match our input string
dateFormatter.dateFormat = "dd-MM-yyyy"
// voila!
var dateFromString = dateFormatter.dateFromString(dateString)

NSDate到字符串

var formatter = NSDateFormatter()
formatter.dateFormat = "dd-MM-yyyy"
let stringDate: String = formatter.stringFromDate(NSDate())
println(stringDate)

objective - c

和陌生人约会

NSString *dateString = @"01-02-2010";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd-MM-yyyy"];
NSDate *dateFromString = [dateFormatter dateFromString:dateString];

首次约会:

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd-MM-yyyy"];
NSString *stringDate = [dateFormatter stringFromDate:[NSDate date]];
NSLog(@"%@", stringDate);

最好的做法是建立一个通用类，你把你所有的通用方法，在几乎所有项目中都有用的方法，并在那里添加@Pavan建议的代码:

+ (NSDate *)getDateOutOfString:(NSString *)passedString andDateFormat:(NSString *)dateFormat{

    NSString *dateString = passedString;
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:dateFormat];
    NSDate *dateFromString = [[NSDate alloc] init];
    dateFromString = [dateFormatter dateFromString:dateString];
    return dateFromString;

}

. .所有其他有用的方法都是如此

通过这样做，你开始为你的应用程序构建一个干净的可重用代码。 干杯!

首次约会还是第一次约会

//This method is used to get NSDate from string 
//Pass the date formate ex-"dd-MM-yyyy hh:mm a"
+ (NSDate*)getDateFromString:(NSString *)dateString withFormate:(NSString *)formate  {

    // Converted date from date string
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"]];
    [dateFormatter setDateFormat:formate];
    NSDate *convertedDate         = [dateFormatter dateFromString:dateString];
    return convertedDate;
}

//This method is used to get the NSString for NSDate
//Pass the date formate ex-"dd-MM-yyyy hh:mm a"
+ (NSString *)getDateStringFromDate:(NSDate *)date withFormate:(NSString *)formate {

    // Converted date from date string
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    //[dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"]];
    [dateFormatter setDateFormat:formate];
    NSString *convertedDate         = [dateFormatter stringFromDate:date];
    return convertedDate;
}

上面的例子不是简单地为Swift 3.0+编写的

更新- Swift 3.0+ -转换日期到字符串

let date = Date() // insert your date data here
var dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd" // add custom format if you'd like 
var dateString = dateFormatter.string(from: date)

字符串到日期

var dateFormatter = DateFormatter()
dateFormatter.format = "dd/MM/yyyy"

var dateFromString: Date? = dateFormatter.date(from: dateString) //pass string here

日期到字符串

 var dateFormatter = DateFormatter()
 dateFormatter.dateFormat = "dd-MM-yyyy"
 let newDate = dateFormatter.string(from: date) //pass Date here