Get directory contents in date modified order

Question

Is there an method to get the contents of a folder in a particular order? I'd like an array of file attribute dictionaries (or just file names) ordered by date modified.

Right now, I'm doing it this way:

• get an array with the file names
• get the attributes of each file
• store the file's path and modified date in a dictionary with the date as a key

Next I have to output the dictionary in date order, but I wondered if there's an easier way? If not, is there a code snippet somewhere which will do this for me?

Thanks.

Solution 1

nall's code above pointed me in the right direction, but I think there are some mistakes in the code as posted above. For instance:

1. Why is filesAndProperties allocated using NMutableDictonary rather than an NSMutableArray?



2. 
   NSDictionary* properties = [[NSFileManager defaultManager]
                                           attributesOfItemAtPath:NSFileModificationDate
                                           error:&error];
   
   

   The code above is passing the wrong parameter for attributesOfItemAtPath - it should be attributesOfItemAtPath:path


3. Your are sorting the files array, but you should be sorting filesAndProperties.

I have implemented the same, with corrections, and using blocks and posted below:

    NSArray *searchPaths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
    NSString* documentsPath = [searchPaths objectAtIndex: 0]; 

    NSError* error = nil;
    NSArray* filesArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsPath error:&error];
    if(error != nil) {
        NSLog(@"Error in reading files: %@", [error localizedDescription]);
        return;
    }

    // sort by creation date
    NSMutableArray* filesAndProperties = [NSMutableArray arrayWithCapacity:[filesArray count]];
    for(NSString* file in filesArray) {
        NSString* filePath = [iMgr.documentsPath stringByAppendingPathComponent:file];
        NSDictionary* properties = [[NSFileManager defaultManager]
                                    attributesOfItemAtPath:filePath
                                    error:&error];
        NSDate* modDate = [properties objectForKey:NSFileModificationDate];

        if(error == nil)
        {
            [filesAndProperties addObject:[NSDictionary dictionaryWithObjectsAndKeys:
                                           file, @"path",
                                           modDate, @"lastModDate",
                                           nil]];                 
        }
    }

        // sort using a block
        // order inverted as we want latest date first
    NSArray* sortedFiles = [filesAndProperties sortedArrayUsingComparator:
                            ^(id path1, id path2)
                            {                               
                                // compare 
                                NSComparisonResult comp = [[path1 objectForKey:@"lastModDate"] compare:
                                                           [path2 objectForKey:@"lastModDate"]];
                                // invert ordering
                                if (comp == NSOrderedDescending) {
                                    comp = NSOrderedAscending;
                                }
                                else if(comp == NSOrderedAscending){
                                    comp = NSOrderedDescending;
                                }
                                return comp;                                
                            }];

Solution 2

How about this:

// Application documents directory
NSURL *documentsURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];

NSArray *directoryContent = [[NSFileManager defaultManager] contentsOfDirectoryAtURL:documentsURL
                                                          includingPropertiesForKeys:@[NSURLContentModificationDateKey]
                                                                             options:NSDirectoryEnumerationSkipsHiddenFiles
                                                                               error:nil];

NSArray *sortedContent = [directoryContent sortedArrayUsingComparator:
                        ^(NSURL *file1, NSURL *file2)
                        {
                            // compare
                            NSDate *file1Date;
                            [file1 getResourceValue:&file1Date forKey:NSURLContentModificationDateKey error:nil];

                            NSDate *file2Date;
                            [file2 getResourceValue:&file2Date forKey:NSURLContentModificationDateKey error:nil];

                            // Ascending:
                            return [file1Date compare: file2Date];
                            // Descending:
                            //return [file2Date compare: file1Date];
                        }];

Solution 3

Simpler...

NSArray*  filelist_sorted;
filelist_sorted = [filelist_raw sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    NSDictionary* first_properties  = [[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithFormat:@"%@/%@", path_thumb, obj1] error:nil];
    NSDate*       first             = [first_properties  objectForKey:NSFileModificationDate];
    NSDictionary* second_properties = [[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithFormat:@"%@/%@", path_thumb, obj2] error:nil];
    NSDate*       second            = [second_properties objectForKey:NSFileModificationDate];
    return [second compare:first];
}];

Solution 4

It's too slow

[[NSFileManager defaultManager]
                                attributesOfItemAtPath:NSFileModificationDate
                                error:&error];

Try this code:

+ (NSDate*) getModificationDateForFileAtPath:(NSString*)path {
    struct tm* date; // create a time structure
    struct stat attrib; // create a file attribute structure

    stat([path UTF8String], &attrib);   // get the attributes of afile.txt

    date = gmtime(&(attrib.st_mtime));  // Get the last modified time and put it into the time structure

    NSDateComponents *comps = [[NSDateComponents alloc] init];
    [comps setSecond:   date->tm_sec];
    [comps setMinute:   date->tm_min];
    [comps setHour:     date->tm_hour];
    [comps setDay:      date->tm_mday];
    [comps setMonth:    date->tm_mon + 1];
    [comps setYear:     date->tm_year + 1900];

    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDate *modificationDate = [[cal dateFromComponents:comps] addTimeInterval:[[NSTimeZone systemTimeZone] secondsFromGMT]];

    [comps release];

    return modificationDate;
}

View more solutions

Comments

[nevan king]

Thanks for the answer. There seems to be a few things that won't work with the iPhone SDK here (NSURLContentModificationDateKey and some other NSURL methods).

[nevan king]

I've started trying to change it to work with the iPhone SDK, but getResourceValue doesn't exist there. I'll look for an array sort for iPhone.

[nall]

nevan, I updated this to work within the constraints of the iPhone SDK

[Roger]

Lots of little bugs in this code fragment ... I don't think this code is tested on iOS.

[Jonathan.]

To invert the ordering you can just multiply the comparison result by -1.

[Admin]

To invert the ordering you can just use return [[path2 objectForKey:@"lastModDate"] compare:[path1 objectForKey:@"lastModDate"]];

[Ivan Kovacevic]

I was just looking for the solution for this myself and ended up using the above code. So I've put it here cause I think its cleaner than what others have provided ;)

[ski_squaw]

This is much faster. 4x faster in my tests. I ran into one bug with this though. My gmtime is returning UTC not GMT. Some times had a one hour difference which caused problems.

[ski_squaw]

Adjust code as follows: NSCalendar *cal = [NSCalendar currentCalendar]; NSTimeZone *tz = [NSTimeZone timeZoneWithAbbreviation:[[NSString alloc] initWithUTF8String:date->tm_zone]]; cal.timeZone = tz;

[Maciej Swic]

You need to #import "sys/stat.h"

[DJTano]

what is path_thumb ?