NSString 到 NSDate

发布于 2024-08-03 19:30:27 字数 663 浏览 1 评论 0原文

我通过使用以下方法获得了一个包含当前日期的字符串：

NSString *date = [[NSDate date] description];

在不同的点上，我想从此字符串中检索日期，并使用了以下代码：

[NSDateFormatter setDefaultFormatterBehavior:NSDateFormatterBehavior10_4];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
//[NSDateFormatter setDefaultFormatterBehavior:NSDateFormatterBehaviorDefault];
[dateFormatter setDateFormat:@"YYYY-MM-DD HH:MM:SS ±HHMM"];

NSDate *dateFromString = [[NSDate alloc] init];
dateFromString = [dateFormatter dateFromString:<NSString containing date>];

我将 dateFromString 获取为 nil< /代码> 0x0。我做错了什么？

原文

I got a string that contains the current date by using this :

NSString *date = [[NSDate date] description];

At a different point I want to retrieve the date from this string and I used the following code:

[NSDateFormatter setDefaultFormatterBehavior:NSDateFormatterBehavior10_4];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
//[NSDateFormatter setDefaultFormatterBehavior:NSDateFormatterBehaviorDefault];
[dateFormatter setDateFormat:@"YYYY-MM-DD HH:MM:SS ±HHMM"];

NSDate *dateFromString = [[NSDate alloc] init];
dateFromString = [dateFormatter dateFromString:<NSString containing date>];

I am getting dateFromString as nil 0x0. What am I doing wrong?

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春夜浅 2024-08-10 19:30:27

您不能发明格式字符串语法并期望它能够工作；您需要实际使用记录的格式。（说真的，“MM”同时表示“月”、“分钟”和“GMT 偏移分钟”？）

正如文档指出，10.4 格式化程序使用 Unicode 格式字符串。

请尝试使用“yyyy-MM-dd HH:mm:ss ZZZ”。

另外，Objective-C 源代码是 ASCII。不要将像 ± 这样的字符放在那里并期望它在任何上下文中都能工作；相反，使用字符串文件。

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海之角 2024-08-10 19:30:27

另外， dateFromString: 返回一个自动释放的 NSDate，所以：

NSDate *dateFromString = [[NSDate alloc] init]; // <- non freed instance
dateFromString = [dateFormatter dateFromString:<NSString containing date>]; // <- new autoreleased instance
....
[dateFromString release]; // <- wrong

您可能想要：

//NSDate *dateFromString = [[NSDate alloc] init];
NSDate *dateFromString = [dateFormatter dateFromString:<NSString containing date>];
....
//[dateFromString release]; // dateFromString is autoreleased

希望这可以拯救某人:)

Also, dateFromString: returns an autoreleased NSDate, so:

NSDate *dateFromString = [[NSDate alloc] init]; // <- non freed instance
dateFromString = [dateFormatter dateFromString:<NSString containing date>]; // <- new autoreleased instance
....
[dateFromString release]; // <- wrong

You may want to:

//NSDate *dateFromString = [[NSDate alloc] init];
NSDate *dateFromString = [dateFormatter dateFromString:<NSString containing date>];
....
//[dateFromString release]; // dateFromString is autoreleased

Hope this could save someone :)

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揽月 2024-08-10 19:30:27

为此制作了一个 NSString 扩展。

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

感谢 NSDataDetector，它识别了一大堆格式。

// Tested in GMT+1 (Hungary).
@"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，获取类别 NSString+EPPZKit.h 来自 GitHub。

原始答案：无论您不确定（或者只是不关心）字符串中包含的日期格式，使用 NSDataDetector 来解析日期。

//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; }];

Made an NSString extension for that.

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

Thanks to NSDataDetector, it recognizes a whole lot of format.

// Tested in GMT+1 (Hungary).
@"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>

Part of eppz!kit, grab the category NSString+EPPZKit.h from GitHub.

ORIGINAL ANSWER: Whether you're not sure (or just don't care) about the date format contained in the string, use NSDataDetector for parsing date.

//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; }];

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红颜悴 2024-08-10 19:30:27

您可以查看 TouchTime。

https://github.com/jheising/TouchTime。

它是 PHP 5.4 中很棒的 strtotime 函数的直接移植，适用于 Cocoa 和 iOS。它将接受几乎任何任意格式的日期或时间字符串并将其转换为 NSDate。

希望它有效，并享受！

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何时共饮酒 2024-08-10 19:30:27

正如前面所回答的，这就是当您发明新语法时会发生的情况。

基于 Apple NSDateFormatter 类参考文档

您可以在样式日期上获取和设置许多属性
格式化程序，...
不过，我们建议您不要更改个别设置。相反，您应该接受初始化时建立的默认设置，并使用 setDateStyle:、setTimeStyle:指定格式

这对于输出特别重要，因为每个区域设置的输出都不同。默认情况下，NSDateFormatter 会观察当前用户的区域设置。因此，相同的 NSDate 可能是 22.11.2011 18:33:19、Nov 22, 2011 6:33:19 PM 或 2011-11-22下午 6:33:19 甚至 २२-११-२०११ ६:३३:१९ अपराह्，全部用于相同的输入和相同的代码。

例如，考虑此代码

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

[dateFormatter setDateStyle:NSDateFormatterShortStyle];
[dateFormatter setTimeStyle:NSDateFormatterShortStyle];

// ShortStyle used: 11/23/37 3:30pm
NSString *dateString = [dateFormatter stringFromDate:date];

检查 Apple 文档以了解 NSDateFormatterStyle 或这个优秀教程

As previously answered, that is what happens when you invent a new sytax.

Based on Apple NSDateFormatter Class Reference documentation

There are many attributes you can get and set on a style date
formatter, ...
You are encouraged, however, not to change individual settings. Instead you should accept the default settings established on initialization and specify the format using setDateStyle:, setTimeStyle:

This is specially important for the output, which is different for every locale. By default NSDateFormatter observes the current user’s locale settings. So the same NSDate could be 22.11.2011 18:33:19, or Nov 22, 2011 6:33:19 PM, or 2011-11-22 下午6:33:19 or even २२-११-२०११ ६:३३:१९ अपराह्, all for the same input and with the same code.

Consider for example this code

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

[dateFormatter setDateStyle:NSDateFormatterShortStyle];
[dateFormatter setTimeStyle:NSDateFormatterShortStyle];

// ShortStyle used: 11/23/37 3:30pm
NSString *dateString = [dateFormatter stringFromDate:date];

Check Apple docs for the different styles of NSDateFormatterStyle or this excellent tutorial

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