使用这个方法将NSString转换为NSdate:

-(NSDate *)getDateFromString:(NSString *)pstrDate
{
    NSDateFormatter* myFormatter = [[NSDateFormatter alloc] init];
    [myFormatter setDateFormat:@"dd/MM/yyyy"];
    NSDate* myDate = [myFormatter dateFromString:pstrDate];
    return myDate;
}

如果现在有人有兴趣在Swift中做这样的事情，我已经开始做了一些事情，尽管它并不完美。

func detectDate(dateString: NSString) -> NSDate {

    var error: NSError?
    let detector: NSDataDetector = NSDataDetector.dataDetectorWithTypes(NSTextCheckingType.Date.toRaw(), error: &error)!

    if error == nil {
        var matches = detector.matchesInString(dateString, options: nil, range: NSMakeRange(0, dateString.length))

        let currentLocale = NSLocale.currentLocale()
        for match in matches {
            match.resultType == NSTextCheckingType.Date
            NSLog("Date: \(match.date.description)")
            return match.date
        }
    }
    return NSDate()
}

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);

当使用固定格式的日期时，需要将日期格式化程序的区域设置为“en_US_POSIX”。

摘自数据格式化指南

If you're working with fixed-format dates, you should first set the locale of the date formatter to something appropriate for your fixed format. In most cases the best locale to choose is en_US_POSIX, a locale that's specifically designed to yield US English results regardless of both user and system preferences. en_US_POSIX is also invariant in time (if the US, at some point in the future, changes the way it formats dates, en_US will change to reflect the new behavior, but en_US_POSIX will not), and between platforms (en_US_POSIX works the same on iPhone OS as it does on OS X, and as it does on other platforms).

Swift 3或更高版本

extension Formatter {
    static let customDate: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.dateFormat = "dd/MM/yy"
        return formatter
    }()
    static let time: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.dateFormat = "HH:mm"
        return formatter
    }()
    static let weekdayName: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "cccc"
        return formatter
    }()
    static let month: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "LLLL"
        return formatter
    }()
}

extension Date {
    var customDate: String {
        return Formatter.customDate.string(from: self)
    }
    var customTime: String {
        return Formatter.time.string(from: self)
    }
    var weekdayName: String {
        return Formatter.weekdayName.string(from: self)
    }
    var monthName: String {
        return Formatter.month.string(from: self)
    }
}

extension String {
    var customDate: Date? {
        return Formatter.customDate.date(from: self)
    }
}

用法:

// this will be displayed like this regardless of the user and system preferences
Date().customTime          //  "16:50"
Date().customDate          //  "06/05/17"
// this will be displayed according to user and system preferences
Date().weekdayName         //  "Saturday"
Date().monthName           //  "May"

解析自定义日期并将日期转换回相同的字符串格式:

let dateString = "01/02/10"

if let date = dateString.customDate {
    print(date.customDate)   // "01/02/10\n"
    print(date.monthName)    // customDate
}

这里是你可以用来定制它的所有元素:

为什么不给NSString添加一个category ?

// NSString+Date.h
@interface NSString (Date)
+ (NSDate*)stringDateFromString:(NSString*)string;
+ (NSString*)stringDateFromDate:(NSDate*)date;
@end


// NSString+Date.m
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:@"EEE, dd MMM yyyy HH:mm:ss ZZZ"];

NSDate *date = [dateFormatter dateFromString:stringDate ];
[dateFormatter release];
+ (NSDateFormatter*)stringDateFormatter
{
    static NSDateFormatter* formatter = nil;
    if (formatter == nil)
    {
        formatter = [[NSDateFormatter alloc] init];
        [formatter setDateFormat:@"EEE, dd MMM yyyy HH:mm:ss ZZZ"];
    }   
    return formatter;
}

+ (NSDate*)stringDateFromString:(NSString*)string
{
    return [[NSString stringDateFormatter] dateFromString:string];
}

+ (NSString*)stringDateFromDate:(NSDate*)date
{
    return [[NSString stringDateFormatter] stringFromDate:date];
}


// Usage (#import "NSString+Date.h") or add in "YOUR PROJECT".pch file
NSString* string = [NSString stringDateFromDate:[NSDate date]];
NSDate* date = [NSString stringDateFromString:string];

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!