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.

Answer 1

Here's an example of how to do it. This approach gets an array of files from the NSFileManager, then sorts that array based on the NSURL property NSURLContentModificationDateKey.

I missed the iPhone tag the first time. I've changed the code to work with the iPhone SDK.

NSInteger lastModifiedSort(id path1, id path2, void* context)
{
    return [[path1 objectForKey:@"lastModDate"] compare:
            [path2 objectForKey:@"lastModDate"]];
}

-(void)filesByModDate
{
    NSString* path = @"/";
    NSError* error = nil;

    NSArray* files = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:path
                                                                         error:&error];
    if(error == nil)
    {
        NSMutableArray* filesAndProperties = [NSMutableDictionary
                                       dictionaryWithCapacity:[files count]];
        for(NSString* path in files)
        {
            NSDictionary* properties = [[NSFileManager defaultManager]
                                        attributesOfItemAtPath:NSFileModificationDate
                                        error:&error];
            NSDate* modDate = [properties objectForKey:NSFileModificationDate];

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

        NSArray* sortedFiles = [files sortedArrayUsingFunction:&lastModifiedSort
                                                       context:nil];

        // SUCCESS!!
        NSLog(@"sortedFiles: %@", sortedFiles);            
    }
    else
    {
        NSLog(@"Encountered error while accessing contents of %@: %@", path, error);
    }
}

Answer 2

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;

}