iOS - 友好的 NSDate 格式

Question

I need to display the date of posts in my app to the user, right now I do it in this format: "Fri, 25 May". How would I format an NSDate to read something like "2 hours ago"? To make it more user friendly.

Answer 1

Take a look at FormaterKit https://github.com/mattt/FormatterKit

Created by mattt who also created AFNetworking.

Answer 2

NSDateFormatter can't do things like that; you're going to need to establish your own rules. I guess something like:

- (NSString *)formattedDate:(NSDate *)date
{
     NSTimeInterval timeSinceDate = [[NSDate date] timeIntervalSinceDate:date];

     // print up to 24 hours as a relative offset
     if(timeSinceDate < 24.0 * 60.0 * 60.0)
     {
         NSUInteger hoursSinceDate = (NSUInteger)(timeSinceDate / (60.0 * 60.0));

         switch(hoursSinceDate)
         {
              default: return [NSString stringWithFormat:@"%d hours ago", hoursSinceDate];
              case 1: return @"1 hour ago";
              case 0:
                  NSUInteger minutesSinceDate = (NSUInteger)(timeSinceDate / 60.0);
                  /* etc, etc */
              break;
         }
     }
     else
     {
          /* normal NSDateFormatter stuff here */
     }
}

So that's to print 'x minutes ago' or 'x hours ago' up to 24 hours from the date, which will usually be one day.

Answer 3

I wanted a date format like Facebook does for their mobile apps so I whipped up this NSDate category - hope it is useful for someone (this kind of stuff should really be in a standard library:) :)

https://github.com/nikilster/NSDate-Time-Ago

Answer 4

There's also SEHumanizedTimeDiff which does/is about to support multiple languages if that's an issue for you:

https://github.com/sarperdag/SEHumanizedTimeDiff

Answer 5

There are about a million ways you could do this, but here's a quick one:

NSString* hoursAgo = [NSString stringWithFormat:@"%.0lf hours ago", fabs([date timeIntervalSinceNow] / 3600.0)]

Of course, this doesn't check that date is actually from the past, doesn't do anything but hours, etc. But, you probably get the idea.

timeIntervalSinceNow returns how many seconds have passed since a given date, with positive numbers being a date in the future and negative numbers being a date in the past. So, we get how many seconds have passed, divide it by 3600 seconds in an hour to compute the hours that have passed, and then put its absolute value into the string "n hours ago".

Answer 6

Here is a pretty good answer this will take in seconds since the epoch(Jan 1, 1970) and return you a nice formatted string like '3 minutes ago'. Simply call it with your date object like so:

[timeAgoFromUnixTime:[myDateObject timeIntervalSince1970]];

+ (NSString *)timeAgoFromUnixTime:(double)seconds
{
    double difference = [[NSDate date] timeIntervalSince1970] - seconds;
    NSMutableArray *periods = [NSMutableArray arrayWithObjects:@"second", @"minute", @"hour", @"day", @"week", @"month", @"year", @"decade", nil];
    NSArray *lengths = [NSArray arrayWithObjects:@60, @60, @24, @7, @4.35, @12, @10, nil];
    int j = 0;
    for(j=0; difference >= [[lengths objectAtIndex:j] doubleValue]; j++)
    {
        difference /= [[lengths objectAtIndex:j] doubleValue];
    }
    difference = roundl(difference);
    if(difference != 1)
    {
        [periods insertObject:[[periods objectAtIndex:j] stringByAppendingString:@"s"] atIndex:j];
    }
    return [NSString stringWithFormat:@"%li %@%@", (long)difference, [periods objectAtIndex:j], @" ago"];
}

Answer 7

In newer versions of iOS since this question was asked, NSDateFormatter has had this ability added. It can now do it using the doesRelativeDateFormatting property.

Answer 8

+(NSString*)HourCalculation:(NSString*)PostDate

{
    NSLog(@"postdate=%@",PostDate);
    // PostDate=@"2014-04-02 01:31:04";
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
    [dateFormat setTimeZone:gmt];
    NSDate *ExpDate = [dateFormat dateFromString:PostDate];
    NSLog(@"expdate=%@",ExpDate);
    NSLog(@"expdate=%@",[NSDate date ]);
    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSDateComponents *components = [calendar components:(NSDayCalendarUnit|NSWeekCalendarUnit|NSMonthCalendarUnit|NSYearCalendarUnit|NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate:ExpDate toDate:[NSDate date] options:0];

//    NSLog(@"year=%d",components.year);
//    
//    NSLog(@"month=%d",components.month);
//    
//    NSLog(@"week=%d",components.week);
//    
//    NSLog(@"day=%d",components.day);
//    
//    NSLog(@"hour=%d",components.hour);
//    
//    NSLog(@"min=%d",components.minute);
//    
//    NSLog(@"sce=%d",components.second);
//    

    NSString *time;

    if(components.year!=0)   
    {
        if(components.year==1) 
        {
            time=[NSString stringWithFormat:@"%ld year",(long)components.year];  
        }
        else{
            time=[NSString stringWithFormat:@"%ld years",(long)components.year]; 
        }    
    }
    else if(components.month!=0) 
    {
        if(components.month==1)   
        {
            time=[NSString stringWithFormat:@"%ld month",(long)components.month]; 
        }
        else{
            time=[NSString stringWithFormat:@"%ld months",(long)components.month]; 
        }
      //  NSLog(@"%@",time);
    }
    else if(components.week!=0)
    {
        if(components.week==1)
        {
            time=[NSString stringWithFormat:@"%ld week",(long)components.week];
        }
        else{
            time=[NSString stringWithFormat:@"%ld weeks",(long)components.week];
        }
       // NSLog(@"%@",time);
    }
    else if(components.day!=0)
    {
        if(components.day==1)   
        {
            time=[NSString stringWithFormat:@"%ld day",(long)components.day];
        }
        else{
            time=[NSString stringWithFormat:@"%ld days",(long)components.day]; 
        } 
    }
    else if(components.hour!=0) 
    {
        if(components.hour==1)  
        {
            time=[NSString stringWithFormat:@"%ld hour",(long)components.hour];  
        }
        else{
            time=[NSString stringWithFormat:@"%ld hours",(long)components.hour];
        }
    }
    else if(components.minute!=0)  
    {
        if(components.minute==1)  
        {
            time=[NSString stringWithFormat:@"%ld min",(long)components.minute];
        }

        else{
            time=[NSString stringWithFormat:@"%ld mins",(long)components.minute]; 
        }
      //  NSLog(@"time=%@",time);
    }
    else if(components.second>=0){

       // NSLog(@"postdate=%@",PostDate);

       // NSLog(@"expdate=%@",[NSDate date ]);

        if(components.second==0)   
        {
            time=[NSString stringWithFormat:@"1 sec"];
        }
        else{
            time=[NSString stringWithFormat:@"%ld secs",(long)components.second];
        }
    }
    return [NSString stringWithFormat:@"%@ ago",time];

}

This code will show you time in ------------sec like 2 sec ago ------------min like 2 mins ago ------------hours like 2 hours ago ------------days like 2 days ago ------------week like 2 weeks ago ------------month like 2 months ago Lastly.... years like 2 years ago:) try this

Answer 9

Adding to the solution try this more simplified method

    NSDateComponents *today = [[NSCalendar currentCalendar] components:NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute|NSCalendarUnitSecond fromDate:passed toDate:[NSDate date] options:0];
    NSTimeInterval interval = [[NSDate date] timeIntervalSinceDate:date];

    if (interval < 60) timestampString = [NSString stringWithFormat:@"%d seconds ago" ,today.second];
    else if (interval < 60 * 60) timestampString = [NSString stringWithFormat:@"%d minutes ago" ,today.minute];
    else if (interval < 60 * 60 * 24) timestampString = [NSString stringWithFormat:@"%d hours ago" ,today.hour];
    else timestampString = [NSString stringWithFormat:@"%d days ago" ,today.day];