关于ios：将NSString转换为NSDate(并再次返回)


Converting NSString to NSDate (and back again)

如何将NSString像"01/02/10"(意思是2010年2月1日)转换为NSDate？ 我怎么能把NSDate变成一个字符串？

相关讨论

斯威夫特4及以后

更新：2018年

字符串到日期

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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)

字符串的日期

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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

更新时间：2017年7月20日

字符串到NSDate

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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String

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

迅速

更新时间：2015年10月22日

字符串到NSDate

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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String

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

Objective-C的

NSString到NSDate

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

NSDate转换为NSString：

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

更新2019年(斯威夫特4)：

为此做了Date扩展。它使用NSDataDetector而不是NSDateFormatter。

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// Just throw at it without any format.
var date: Date? = Date.FromString("02-14-2019 17:05:05")

非常愉快，它甚至可以识别"明天在5"这样的事情。

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XCTAssertEqual(Date.FromString("2019-02-14"),                    Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("2019.02.14"),                    Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("2019/02/14"),                    Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("2019 Feb 14"),                   Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("2019 Feb 14th"),                 Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("20190214"),                      Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("02-14-2019"),                    Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("02.14.2019 5:00 PM"),            Date.FromCalendar(2019, 2, 14, 17))
XCTAssertEqual(Date.FromString("02/14/2019 17:00"),              Date.FromCalendar(2019, 2, 14, 17))
XCTAssertEqual(Date.FromString("14 February 2019 at 5 hour"),    Date.FromCalendar(2019, 2, 14, 17))
XCTAssertEqual(Date.FromString("02-14-2019 17:05:05"),           Date.FromCalendar(2019, 2, 14, 17, 05, 05))
XCTAssertEqual(Date.FromString("17:05, 14 February 2019 (UTC)"), Date.FromCalendar(2019, 2, 14, 17, 05))
XCTAssertEqual(Date.FromString("02-14-2019 17:05:05 GMT"),       Date.FromCalendar(2019, 2, 14, 17, 05, 05))
XCTAssertEqual(Date.FromString("02-13-2019 Tomorrow"),           Date.FromCalendar(2019, 2, 14))
XCTAssertEqual(Date.FromString("2019 Feb 14th Tomorrow at 5"),   Date.FromCalendar(2019, 2, 14, 17))

如下：

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extension Date
{


    public static func FromString(_ dateString: String) -> Date?
    {
        // Date detector.
        let detector = try! NSDataDetector(types: NSTextCheckingResult.CheckingType.date.rawValue)

        // Enumerate matches.
        var matchedDate: Date?
        var matchedTimeZone: TimeZone?
        detector.enumerateMatches(
            in: dateString,
            options: [],
            range: NSRange(location: 0, length: dateString.utf16.count),
            using:
            {
                (eachResult, _, _) in

                // Lookup matches.
                matchedDate = eachResult?.date
                matchedTimeZone = eachResult?.timeZone

                // Convert to GMT (!) if no timezone detected.
                if matchedTimeZone == nil, let detectedDate = matchedDate
                { matchedDate = Calendar.current.date(byAdding: .second, value: TimeZone.current.secondsFromGMT(), to: detectedDate)! }
        })

        // Result.
        return matchedDate
    }
}

更新2014年：

为此做了一个NSString扩展。

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// Simple as this.  
date = dateString.dateValue;

感谢NSDataDetector，它识别了很多格式。

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'2014-01-16' dateValue is <2014-01-16 11:00:00 +0000>
'2014.01.16' dateValue is <2014-01-16 11:00:00 +0000>
'2014/01/16' dateValue is <2014-01-16 11:00:00 +0000>
'2014 Jan 16' dateValue is <2014-01-16 11:00:00 +0000>
'2014 Jan 16th' dateValue is <2014-01-16 11:00:00 +0000>
'20140116' dateValue is <2014-01-16 11:00:00 +0000>
'01-16-2014' dateValue is <2014-01-16 11:00:00 +0000>
'01.16.2014' dateValue is <2014-01-16 11:00:00 +0000>
'01/16/2014' dateValue is <2014-01-16 11:00:00 +0000>
'16 January 2014' dateValue is <2014-01-16 11:00:00 +0000>
'01-16-2014 17:05:05' dateValue is <2014-01-16 16:05:05 +0000>
'01-16-2014 T 17:05:05 UTC' dateValue is <2014-01-16 17:05:05 +0000>
'17:05, 1 January 2014 (UTC)' dateValue is <2014-01-01 16:05:00 +0000>

eppz！kit的一部分，从GitHub获取NSString + EPPZKit.h类别。

原始答案2013：

无论您是否(或不关心)字符串中包含的日期格式，请使用NSDataDetector来解析日期。

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//Role players.
NSString *dateString = @"Wed, 03 Jul 2013 02:16:02 -0700";
__block NSDate *detectedDate;

//Detect.
NSDataDetector *detector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingAllTypes error:nil];
[detector enumerateMatchesInString:dateString
                           options:kNilOptions
                             range:NSMakeRange(0, [dateString length])
                        usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop)
{ detectedDate = result.date; }];
相关讨论

使用固定格式日期时，您需要将日期格式化程序区域设置为"en_US_POSIX"。

取自数据格式指南

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

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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
    }()
}
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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：

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// 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：

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let dateString ="01/02/10"

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

在这里，您可以使用所有元素来根据需要自定义它：

enter image description here

相关讨论

为什么不向NSString添加类别？

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// 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];
相关讨论

使用"10"代表一年并不好，因为它可能是1910年，1810年等。你可能应该使用4位数。

如果你可以改变日期

1
yyyymmdd

然后你可以使用：

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// Convert string to date object
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyyMMdd"];
NSDate *date = [dateFormat dateFromString:dateStr];  

// Convert date object to desired output format
[dateFormat setDateFormat:@"EEEE MMMM d, YYYY"];
dateStr = [dateFormat stringFromDate:date];  
[dateFormat release];
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NSString *dateStr = @"Tue, 25 May 2010 12:53:58 +0000";

// Convert string to date object
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"EE, d LLLL yyyy HH:mm:ss Z"];
NSDate *date = [dateFormat dateFromString:dateStr];
[dateFormat release];

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// Convert string to date

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyyMMdd"];
NSDate *date = [dateFormat dateFromString:dateStr];  

// Convert Date to string

[dateFormat setDateFormat:@"EEEE MMMM d, YYYY"];
dateStr = [dateFormat stringFromDate:date];  
[dateFormat release];

使用此方法从NSString转换为NSdate：

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

NSCalendar *cal = [NSCalendar currentCalendar];
NSDate *now = [dateFormatter dateFromString:mystr];

Nslog(@"%@",now);

如果要设置格式，请使用以下代码：

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NSString *dateString = @"01-02-2010";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

// this is important - we set our input date format to match our input string
// if format doesn't match you'll get nil from your string, so be careful
[dateFormatter setDateFormat:@"dd-MM-yyyy"];
NSDate *dateFromString = [[NSDate alloc] init];

// voila!
dateFromString = [dateFormatter dateFromString:dateString];
Nslog(@"%@",[dateFormatter dateFromString:dateString]);

如果有人有兴趣在Swift这样做这样的事情，我有一个开始的东西，虽然它并不完美。

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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()
}

NSString的日期

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NSString *dateString = [NSString stringWithFormat:@"%@",[NSDate date]];
NSLog(@"string: %@",dateString ); //2015-03-24 12:28:49 +0000

NSString到NSDate

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NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
NSDate *date = [formatter dateFromString:dateString];
NSLog(@"date: %@", date); //015-03-24 12:28:49 +0000

字符串到目前为止

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

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

字符串日期

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

最佳实践是建立一个通用类，您可以将所有常用方法，方法用于几乎所有项目，并将@Pavan建议的代码添加为：

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+ (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;

}

..等等所有其他有用的方法

通过这样做，您可以开始为您的应用程序构建一个干净的可重用代码。
干杯!

按照Swift 2.2

您可以从NSDate中的String和String中轻松获取NSDate。
例如

首先设置日期格式化程序

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let formatter = NSDateFormatter();
formatter.dateStyle = NSDateFormatterStyle.MediumStyle
formatter.timeStyle = .NoStyle
formatter.dateFormat ="MM/dd/yyyy"

现在从字符串获取日期，反之亦然。

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let strDate = formatter.stringFromDate(NSDate())
print(strDate)
let dateFromStr = formatter.dateFromString(strDate)
print(dateFromStr)

现在享受。

NSString到NSDate或NSDate到NSString

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//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;
}

以上示例不仅仅是针对Swift 3.0+编写的

更新 - Swift 3.0+ - 将日期转换为字符串

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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)

您可以使用扩展名。

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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，执行实际代码将如下所示

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

还有一些默认方法，但我想它可能不适用于您从文档中提供的格式

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