NSDate返回小时/天/周

Question

在Instagram程序中捕捉，日期显示为（例如）2小时前/ 3天前/ 1周前..我有“2013-03-20 16:02:48”。 。我怎样才能得到字符串“2天前”？

Answer 1

考虑使用NSCalendar和NSDateComponents来计算差异并清晰地表达与最终用户类似的内容。

Answer 2

有一个开源项目

https://github.com/billgarrison/SORelativeDateTransformer

从它的文档：

例如，在当前日期时间为2010-12-05 11:30，然后
... 2010-12-05 11:00转换为“30分钟前”
... 2010-12-01 11:00转换为“5天前”
... 2010-12- 25 08:00是tr ansformed为“在2个星期”

// Display a file's creation date relative to today's date 
NSURL *someFilePath = ...; 
NSDictionary *attribs = [[NSFileManager defaultManager] attributesOfItemAtPath:someFilePath error:NULL]; 

NSDate *dateModified = [attribs fileModificationDate]; 

// fileModificationDate is 2010-10-01 12:00:00TZ; 
// Date now is 2010-10-30 12:00:00TZ 

SORelativeDateTransformer *relativeDateTransformer = [[SORelativeDateTransformer alloc] init]; 
NSString *relativeDate = [relativeDateTransformer transformedValue: dateModified]; 

NSLog (@"This file was modified %@.", relativeDate); // ==> "This file was modified 3 weeks ago." 

Answer 3

也许有什么地方出库，这将做到这一点你。

但是不管怎样都不难。有可能将NSDate分解为其组件。然后很容易比较它们，并编写一些如果其他代码覆盖所有需要的情况。

下面是从我的项目之一，我解决过去7天的日期，以适当的平日一个例子：

NSString *resultDateString; 

// First, reduce the two dates we want to compare to the scope of days by erasing hours, minutes and seconds 

unsigned int flagA = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit; 
NSDateComponents *compsA = [[NSCalendar currentCalendar] components:flagA fromDate:myObjectsDate]; 
[compsA setHour:0]; 
[compsA setMinute:0]; 
[compsA setSecond:0]; 
NSDate *checkDate = [[NSCalendar currentCalendar] dateFromComponents:compsA]; 

unsigned int flagB = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit; 
NSDateComponents *partsB = [[NSCalendar currentCalendar] components:flagB fromDate:[NSDate date]]; 
[compsB setHour:0]; 
[compsB setMinute:0]; 
[compsB setSecond:0]; 
NSDate *nowDate = [[NSCalendar currentCalendar] dateFromComponents:compsB]; 

// Get the interval between the two dates, interval is still in seconds, but since it is calculated using days only, it will be precisely 0 if the day is the same  

NSTimeInterval interval = [searchDate timeIntervalSinceDate:nowDate]; 

// check if the objects date is today. If it isn't, find out which day it is and name it appropriately 

if (interval == 0) { 

    resultDateString = [NSString stringWithString:@"Today"]; 

} else { 

    unsigned int flagC = NSWeekdayCalendarUnit; 
    NSDateComponents *compsC = [[NSCalendar currentCalendar] components:flagC fromDate:myObjectsDate]; 

    switch ([compsC weekday]) { 
     case 1: 
      resultDateString = @"Sunday"; 
      break; 
     case 2: 
      resultDateString = @"Monday"; 
      break; 
     case 3: 
      resultDateString = @"Tuesday"; 
      break; 
     case 4: 
      resultDateString = @"Wednesday"; 
      break; 
     case 5: 
      resultDateString = @"Thursday"; 
      break; 
     case 6: 
      resultDateString = @"Friday"; 
      break; 
     case 7: 
      resultDateString = @"Saturday"; 
      break; 

     default: 
      break; 
    } 

} 

这仅仅是一个摘录，请注意，这个代码片断不检查例如，如果间隔时间超过7天，因为我在代码中以不同的方式覆盖了这些情况。但我认为它会给你一个如何做到这一点的基本想法。