Get directory contents in date modified order - iphone

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

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:
Why is filesAndProperties allocated using NMutableDictonary rather than an NSMutableArray?
NSDictionary* properties = [[NSFileManager defaultManager]
attributesOfItemAtPath:NSFileModificationDate
error:&error];
The code above is passing the wrong parameter for attributesOfItemAtPath - it should be attributesOfItemAtPath:path
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;
}];

Answer 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];
}];

Answer 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];
}];

Answer 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;
}

Answer 5

Code does not work in iPhone SDK, full of compilation error. Please find updated code
`
NSInteger lastModifiedSort(id path1, id path2, void* context)
{
int comp = [[path1 objectForKey:#"lastModDate"] compare:
[path2 objectForKey:#"lastModDate"]];
return comp;
}
-(NSArray *)filesByModDate:(NSString*) path{
NSError* error = nil;
NSArray* filesArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:path
error:&error];
if(error == nil)
{
NSMutableArray* filesAndProperties = [NSMutableArray arrayWithCapacity:[filesArray count]];
for(NSString* imgName in filesArray)
{
NSString *imgPath = [NSString stringWithFormat:#"%#/%#",path,imgName];
NSDictionary* properties = [[NSFileManager defaultManager]
attributesOfItemAtPath:imgPath
error:&error];
NSDate* modDate = [properties objectForKey:NSFileModificationDate];
if(error == nil)
{
[filesAndProperties addObject:[NSDictionary dictionaryWithObjectsAndKeys:
imgName, #"path",
modDate, #"lastModDate",
nil]];
}else{
NSLog(#"%#",[error description]);
}
}
NSArray* sortedFiles = [filesAndProperties sortedArrayUsingFunction:&lastModifiedSort context:nil];
NSLog(#"sortedFiles: %#", sortedFiles);
return sortedFiles;
}
else
{
NSLog(#"Encountered error while accessing contents of %#: %#", path, error);
}
return filesArray;
}
`