objective-c iPhone：将日期字符串转换为相对时间戳

iPhone: Convert date string to a relative time stamp

提问by Gilean

I've got a timestamp as a string like:

我有一个时间戳作为一个字符串：

Thu, 21 May 09 19:10:09 -0700

星期四，5 月 21 日 09 19:10:09 -0700

and I'd like to convert it to a relative time stamp like '20 minutes ago' or '3 days ago'.

我想将其转换为相对时间戳，例如“20 分钟前”或“3 天前”。

What's the best way to do this using Objective-C for the iPhone?

在 iPhone 上使用 Objective-C 的最佳方法是什么？

回答by Gilean

-(NSString *)dateDiff:(NSString *)origDate {
    NSDateFormatter *df = [[NSDateFormatter alloc] init];
    [df setFormatterBehavior:NSDateFormatterBehavior10_4];
    [df setDateFormat:@"EEE, dd MMM yy HH:mm:ss VVVV"];
    NSDate *convertedDate = [df dateFromString:origDate];
    [df release];
    NSDate *todayDate = [NSDate date];
    double ti = [convertedDate timeIntervalSinceDate:todayDate];
    ti = ti * -1;
    if(ti < 1) {
        return @"never";
    } else  if (ti < 60) {
        return @"less than a minute ago";
    } else if (ti < 3600) {
        int diff = round(ti / 60);
        return [NSString stringWithFormat:@"%d minutes ago", diff];
    } else if (ti < 86400) {
        int diff = round(ti / 60 / 60);
        return[NSString stringWithFormat:@"%d hours ago", diff];
    } else if (ti < 2629743) {
        int diff = round(ti / 60 / 60 / 24);
        return[NSString stringWithFormat:@"%d days ago", diff];
    } else {
        return @"never";
    }   
}

回答by stefanB

Here are methods from Cocoa to help you to get relevant info (not sure if they are all available in coca-touch).

以下是 Cocoa 提供的方法，可帮助您获取相关信息（不确定它们是否都在 coca-touch 中可用）。

    NSDate * today = [NSDate date];
    NSLog(@"today: %@", today);

    NSString * str = @"Thu, 21 May 09 19:10:09 -0700";
    NSDate * past = [NSDate dateWithNaturalLanguageString:str
                            locale:[[NSUserDefaults 
                            standardUserDefaults] dictionaryRepresentation]];

    NSLog(@"str: %@", str);
    NSLog(@"past: %@", past);

    NSCalendar *gregorian = [[NSCalendar alloc]
                             initWithCalendarIdentifier:NSGregorianCalendar];
    unsigned int unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | 
                             NSDayCalendarUnit | 
                             NSHourCalendarUnit | NSMinuteCalendarUnit | 
                             NSSecondCalendarUnit;
    NSDateComponents *components = [gregorian components:unitFlags
                                                fromDate:past
                                                  toDate:today
                                                 options:0];

    NSLog(@"months: %d", [components month]);
    NSLog(@"days: %d", [components day]);
    NSLog(@"hours: %d", [components hour]);
    NSLog(@"seconds: %d", [components second]);

The NSDateComponents object seems to hold the difference in relevant units (as specified). If you specify all units you can then use this method:

NSDateComponents 对象似乎在相关单位（如指定）中保持差异。如果指定所有单位，则可以使用此方法：

void dump(NSDateComponents * t)
{
    if ([t year]) NSLog(@"%d years ago", [t year]);
    else if ([t month]) NSLog(@"%d months ago", [t month]);
    else if ([t day]) NSLog(@"%d days ago", [t day]);
    else if ([t minute]) NSLog(@"%d minutes ago", [t minute]);
    else if ([t second]) NSLog(@"%d seconds ago", [t second]);
}

If you want to calculate yourself you can have a look at:

如果你想自己计算，你可以看看：

NSDate timeIntervalSinceDate

And then use seconds in the algorithm.

然后在算法中使用秒。

Disclaimer: If this interface is getting deprecated (I haven't checked), Apple's preferred way of doing this via NSDateFormatters, as suggested in comments below, looks pretty neat as well - I'll keep my answer for historical reasons, it may still be useful for some to look at the logic used.

免责声明：如果此界面已被弃用（我还没有检查过），Apple 的首选方法（NSDateFormatters如下面评论中所建议的）看起来也很简洁 - 由于历史原因，我将保留我的答案，它可能仍然是对一些查看使用的逻辑很有用。

回答by Carl Coryell-Martin

I can't edit yet, but I took Gilean's code and made a couple of tweaks and made it a category of NSDateFormatter.

我还不能编辑，但我采用了 Gilean 的代码并进行了一些调整，使其成为 NSDateFormatter 的一个类别。

It accepts a format string so it will work w/ arbitrary strings and I added if clauses to have singular events be grammatically correct.

它接受格式字符串，因此它可以使用任意字符串工作，并且我添加了 if 子句以使单数事件在语法上是正确的。

Cheers,

干杯，

Carl C-M

卡尔·CM

@interface NSDateFormatter (Extras)
+ (NSString *)dateDifferenceStringFromString:(NSString *)dateString
                                  withFormat:(NSString *)dateFormat;

@end

@implementation NSDateFormatter (Extras)

+ (NSString *)dateDifferenceStringFromString:(NSString *)dateString
                                  withFormat:(NSString *)dateFormat
{
  NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
  [dateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
  [dateFormatter setDateFormat:dateFormat];
  NSDate *date = [dateFormatter dateFromString:dateString];
  [dateFormatter release];
  NSDate *now = [NSDate date];
  double time = [date timeIntervalSinceDate:now];
  time *= -1;
  if(time < 1) {
    return dateString;
  } else if (time < 60) {
    return @"less than a minute ago";
  } else if (time < 3600) {
    int diff = round(time / 60);
    if (diff == 1) 
      return [NSString stringWithFormat:@"1 minute ago", diff];
    return [NSString stringWithFormat:@"%d minutes ago", diff];
  } else if (time < 86400) {
    int diff = round(time / 60 / 60);
    if (diff == 1)
      return [NSString stringWithFormat:@"1 hour ago", diff];
    return [NSString stringWithFormat:@"%d hours ago", diff];
  } else if (time < 604800) {
    int diff = round(time / 60 / 60 / 24);
    if (diff == 1) 
      return [NSString stringWithFormat:@"yesterday", diff];
    if (diff == 7) 
      return [NSString stringWithFormat:@"last week", diff];
    return[NSString stringWithFormat:@"%d days ago", diff];
  } else {
    int diff = round(time / 60 / 60 / 24 / 7);
    if (diff == 1)
      return [NSString stringWithFormat:@"last week", diff];
    return [NSString stringWithFormat:@"%d weeks ago", diff];
  }   
}

@end

回答by Chris Ladd

In the interest of completeness, based on a @Gilean's answer, here's the complete code for a simple category on NSDate that mimics rails' nifty date helpers. For a refresher on categories, these are instance methods that you would call on NSDate objects. So, if I have an NSDate that represents yesterday, [myDate distanceOfTimeInWordsToNow] => "1 day".

为了完整起见，基于@Gilean 的回答，这里是 NSDate 上一个简单类别的完整代码，它模仿了 Rails 的漂亮日期助手。为了复习类别，这些是您将在 NSDate 对象上调用的实例方法。所以，如果我有一个代表昨天的 NSDate，[myDate distanceOfTimeInWordsToNow] =>“1 天”。

Hope it's useful!

希望有用！

@interface NSDate (NSDate_Relativity)

-(NSString *)distanceOfTimeInWordsSinceDate:(NSDate *)aDate;
-(NSString *)distanceOfTimeInWordsToNow;

@end



@implementation NSDate (NSDate_Relativity)


-(NSString *)distanceOfTimeInWordsToNow {
    return [self distanceOfTimeInWordsSinceDate:[NSDate date]];

}

-(NSString *)distanceOfTimeInWordsSinceDate:(NSDate *)aDate {
    double interval = [self timeIntervalSinceDate:aDate];

    NSString *timeUnit;
    int timeValue;

    if (interval < 0) {
        interval = interval * -1;        
    }

    if (interval< 60) {
        return @"seconds";

    } else if (interval< 3600) { // minutes

        timeValue = round(interval / 60);

        if (timeValue == 1) {
            timeUnit = @"minute";

        } else {
            timeUnit = @"minutes";

        }


    } else if (interval< 86400) {
        timeValue = round(interval / 60 / 60);

        if (timeValue == 1) {
            timeUnit = @"hour";

        } else {
            timeUnit = @"hours";
        }


    } else if (interval< 2629743) {
        int days = round(interval / 60 / 60 / 24);

        if (days < 7) {

            timeValue = days;

            if (timeValue == 1) {
                timeUnit = @"day";
            } else {
                timeUnit = @"days";
            }

        } else if (days < 30) {
            int weeks = days / 7;

            timeValue = weeks;

            if (timeValue == 1) {
                timeUnit = @"week";
            } else {
                timeUnit = @"weeks";
            }


        } else if (days < 365) {

            int months = days / 30;
            timeValue = months;

            if (timeValue == 1) {
                timeUnit = @"month";
            } else {
                timeUnit = @"months";
            }

        } else if (days < 30000) { // this is roughly 82 years. After that, we'll say 'forever'
            int years = days / 365;
            timeValue = years;

            if (timeValue == 1) {
                timeUnit = @"year";
            } else {
                timeUnit = @"years";
            }

        } else {
            return @"forever ago";
        }
    }

    return [NSString stringWithFormat:@"%d %@", timeValue, timeUnit];

}

@end

回答by Dean Kelly

There are already a lot of answers that come to the same solution but it can't hurt to have choices. Here's what I came up with.

对于相同的解决方案，已经有很多答案，但有选择也无妨。这是我想出的。

- (NSString *)stringForTimeIntervalSinceCreated:(NSDate *)dateTime
{
    NSDictionary *timeScale = @{@"second":@1,
                                @"minute":@60,
                                @"hour":@3600,
                                @"day":@86400,
                                @"week":@605800,
                                @"month":@2629743,
                                @"year":@31556926};
    NSString *scale;
    int timeAgo = 0-(int)[dateTime timeIntervalSinceNow];
    if (timeAgo < 60) {
        scale = @"second";
    } else if (timeAgo < 3600) {
        scale = @"minute";
    } else if (timeAgo < 86400) {
        scale = @"hour";
    } else if (timeAgo < 605800) {
        scale = @"day";
    } else if (timeAgo < 2629743) {
        scale = @"week";
    } else if (timeAgo < 31556926) {
        scale = @"month";
    } else {
        scale = @"year";
    }

    timeAgo = timeAgo/[[timeScale objectForKey:scale] integerValue];
    NSString *s = @"";
    if (timeAgo > 1) {
        s = @"s";
    } 
    return [NSString stringWithFormat:@"%d %@%@ ago", timeAgo, scale, s];
}

回答by malhal

I took Carl Coryell-Martin's code and made a simpler NSDate category that doesn't have warnings about the string formatting of the singulars, and also tidys up the week ago singular:

我采用了 Carl Coryell-Martin 的代码并制作了一个更简单的 NSDate 类别，该类别没有关于单数字符串格式的警告，并且还整理了一周前的单数：

@interface NSDate (Extras)
- (NSString *)differenceString;
@end

@implementation NSDate (Extras)

- (NSString *)differenceString{
    NSDate* date = self;
    NSDate *now = [NSDate date];
    double time = [date timeIntervalSinceDate:now];
    time *= -1;
    if (time < 60) {
        int diff = round(time);
        if (diff == 1)
            return @"1 second ago";
        return [NSString stringWithFormat:@"%d seconds ago", diff];
    } else if (time < 3600) {
        int diff = round(time / 60);
        if (diff == 1)
            return @"1 minute ago";
        return [NSString stringWithFormat:@"%d minutes ago", diff];
    } else if (time < 86400) {
        int diff = round(time / 60 / 60);
        if (diff == 1)
            return @"1 hour ago";
        return [NSString stringWithFormat:@"%d hours ago", diff];
    } else if (time < 604800) {
        int diff = round(time / 60 / 60 / 24);
        if (diff == 1)
            return @"yesterday";
        if (diff == 7)
            return @"a week ago";
        return[NSString stringWithFormat:@"%d days ago", diff];
    } else {
        int diff = round(time / 60 / 60 / 24 / 7);
        if (diff == 1)
            return @"a week ago";
        return [NSString stringWithFormat:@"%d weeks ago", diff];
    }   
}

@end

回答by dimpiax

In Swift

在斯威夫特

Usage:

用法：

let time = NSDate(timeIntervalSince1970: timestamp).timeIntervalSinceNow
let relativeTimeString = NSDate.relativeTimeInString(time)
println(relativeTimeString)

Extension:

延期：

extension NSDate {
    class func relativeTimeInString(value: NSTimeInterval) -> String {
        func getTimeData(value: NSTimeInterval) -> (count: Int, suffix: String) {
            let count = Int(floor(value))
            let suffix = count != 1 ? "s" : ""
            return (count: count, suffix: suffix)
        }

        let value = -value
        switch value {
            case 0...15: return "just now"

            case 0..<60:
                let timeData = getTimeData(value)
                return "\(timeData.count) second\(timeData.suffix) ago"

            case 0..<3600:
                let timeData = getTimeData(value/60)
                return "\(timeData.count) minute\(timeData.suffix) ago"

            case 0..<86400:
                let timeData = getTimeData(value/3600)
                return "\(timeData.count) hour\(timeData.suffix) ago"

            case 0..<604800:
                let timeData = getTimeData(value/86400)
                return "\(timeData.count) day\(timeData.suffix) ago"

            default:
                let timeData = getTimeData(value/604800)
                return "\(timeData.count) week\(timeData.suffix) ago"
        }
    }
}

回答by ppaulojr

My solution:

我的解决方案：

- (NSString *) dateToName:(NSDate*)dt withSec:(BOOL)sec {

    NSLocale *locale = [NSLocale currentLocale];
    NSTimeInterval tI = [[NSDate date] timeIntervalSinceDate:dt];
    if (tI < 60) {
      if (sec == NO) {
           return NSLocalizedString(@"Just Now", @"");
       }
       return [NSString stringWithFormat:
                 NSLocalizedString(@"%d seconds ago", @""),(int)tI];
     }
     if (tI < 3600) {
       return [NSString stringWithFormat:
                 NSLocalizedString(@"%d minutes ago", @""),(int)(tI/60)];
     }
     if (tI < 86400) {
      return [NSString stringWithFormat:
                 NSLocalizedString(@"%d hours ago", @""),(int)tI/3600];
     }

     NSDateFormatter *relativeDateFormatter = [[NSDateFormatter alloc] init];
     [relativeDateFormatter setTimeStyle:NSDateFormatterNoStyle];
     [relativeDateFormatter setDateStyle:NSDateFormatterMediumStyle];
     [relativeDateFormatter setDoesRelativeDateFormatting:YES];
     [relativeDateFormatter setLocale:locale];

     NSString * relativeFormattedString = 
            [relativeDateFormatter stringForObjectValue:dt];
     return relativeFormattedString;
}

回答by Nael El Shawwa

Use the NSDate class:

使用 NSDate 类：

timeIntervalSinceDate

returns the interval in seconds.

以秒为单位返回间隔。

Quick exercise to implement this in objective-c:

在objective-c中快速练习：

1. Get time "now" NSDate
2. Get the NSDate you wish to compare with
3. Get the interval in seconds using timeIntervalSinceDate

1. 获取时间“现在”NSDate
2. 获取您希望与之比较的 NSDate
3. 使用 timeIntervalSinceDate 获取以秒为单位的间隔

Then implement this pseudo code:

然后实现这个伪代码：

if (x < 60) // x seconds ago

else if( x/60 < 60) // floor(x/60) minutes ago

else if (x/(60*60) < 24) // floor(x/(60*60) hours ago

else if (x/(24*60*60) < 7) // floor(x(24*60*60) days ago

and so on...

等等...

then you need to decide whether a month is 30,31 or 28 days. Keep it simple - pick 30.

那么您需要决定一个月是 30,31 天还是 28 天。保持简单 - 选择 30。

There might be a better way, but its 2am and this is the first thing that came to mind...

可能有更好的方法，但它是凌晨 2 点，这是我想到的第一件事......

回答by Bluephlame

Not sure why this isnt in cocoa-touch, i nice standard way of doing this would be great.

不知道为什么这不是可可触摸，我很好的标准方式这样做会很棒。

Set up some types to keep the data in, it will make it easier if you ever ned to localise it a bit more. (obviously expand if you need more time periods)

设置一些类型来保存数据，如果你需要更多地本地化它会更容易。（如果您需要更多时间段，显然可以扩展）

typedef struct DayHours {
    int Days;
    double Hours;
} DayHours;


+ (DayHours) getHourBasedTimeInterval:(double) hourBased withHoursPerDay:(double) hpd
{
    int NumberOfDays = (int)(fabs(hourBased) / hpd);
    float hoursegment = fabs(hourBased) - (NumberOfDays * hpd);
    DayHours dh;
    dh.Days = NumberOfDays;
    dh.Hours = hoursegment;
    return dh;
}

NOTE: I"m using an hour based calculation , as that is what my data is in. NSTimeInterval is second based. I also had to convert between the two.

注意：我正在使用基于小时的计算，因为这就是我的数据所在。NSTimeInterval 是第二个。我还必须在两者之间进行转换。