How to sort files by modified date in iOS - iphone

Question

I used NSFileManager to retrieve the files in a folder, and I want to sort them by modified date. How to do that ?
Thanks.

Answer 1

What have you tried so far?
I haven't done this, but a quick look at the docs makes me think that you should try the following:
Call -contentsOfDirectoryAtURL:includingPropertiesForKeys:options:error: and specify NSURLContentModificationDateKey as one of the keys.
You'll get back an array of NSURL objects which you can then sort using an NSArray method like -sortedArrayUsingComparator:.
Pass in a comparator block that looks up the modification date for each NSURL using -getResourceValue:forKey:error:.
Update: When I wrote the answer above, -getResourceValue:forKey:error: existed in iOS but didn't do anything. That method is now functional as of iOS 5. The following code will log an app's resource files followed by a list of corresponding modification dates:
NSFileManager *manager = [NSFileManager defaultManager];
NSArray *files = [manager contentsOfDirectoryAtURL:[[NSBundle mainBundle] resourceURL]
includingPropertiesForKeys:[NSArray arrayWithObject:NSURLContentModificationDateKey]
options:nil
error:nil];
NSMutableArray *dates = [NSMutableArray array];
for (NSURL *f in files) {
NSDate *d = nil;
if ([f getResourceValue:&d forKey:NSURLContentModificationDateKey error:nil]) {
[dates addObject:d];
}
}
NSLog(#"Files: %#", files);
NSLog(#"Dates: %#", dates);

Answer 2

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSFileManager *manager = [NSFileManager defaultManager];
NSArray *imageFilenames = [manager contentsOfDirectoryAtPath:documentsDirectory error:nil];
NSMutableArray *originalImage = [[NSMutableArray alloc]init];
for (int i = 1; i < [imageFilenames count]; i++)
{
NSString *imageName = [NSString stringWithFormat:#"%#/%#",documentsDirectory,[imageFilenames objectAtIndex:i] ];
}
//---------sorting image by date modified
NSArray* filelist_date_sorted;
filelist_date_sorted = [imageFilenames sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2)
{
NSDictionary* first_properties = [[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithFormat:#"%#/%#", documentsDirectory, obj1] error:nil];
NSDate *first = [first_properties objectForKey:NSFileCreationDate];
NSDictionary *second_properties = [[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithFormat:#"%#/%#", documentsDirectory, obj2] error:nil];
NSDate *second = [second_properties objectForKey:NSFileCreationDate];
return [second compare:first];
}];
NSLog(#" Date sorted result is %#",filelist_date_sorted);

Answer 3

static static NSInteger contentsOfDirSort(NSString *left, NSString *right, void *ptr) {
(void)ptr;
struct stat finfo_l, r_finfo_r;
if(-1 == stat([left UTF8String], &finfo_l))
return NSOrderedSame;
if(-1 == stat([right UTF8String], &finfo_r))
return NSOrderedSame;
if(finfo_l.st_mtime < finfo_r.st_mtime)
return NSOrderedAscending;
if(finfo_l.st_mtime > finfo_r.st_mtime)
return NSOrderedDescending;
return NSOrderedSame;
}
Now, later on in your code.
NSMutableArray *mary = [NSMutableArray arrayWithArray:filePathsArray];
[mary sortUsingFunction:contentsOfDirSort context:nil];
// Use mary...

Answer 4

Quick Method:
-(void)dateModified
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSFileManager *manager = [NSFileManager defaultManager];
NSArray *fileList = [manager contentsOfDirectoryAtPath:documentsDirectory error:nil];
//--- Listing file by name sort
NSLog(#"\n File list %#",fileList);
int num;
//-- Listing file name with modified dated
for (NSString *s in fileList)
{
NSString *filestring = [documentsDirectory stringByAppendingFormat:#"/%#",s];
NSDictionary *filePathsArray1 = [[NSFileManager defaultManager] attributesOfItemAtPath:filestring error:nil];
NSString *modifiedDate = [filePathsArray1 objectForKey:NSFileModificationDate];
NSLog(#"\n Modified Day : %#", modifiedDate);
num=num+1;
}
}

Answer 5

In a category over NSFileManager:
static NSInteger contentsOfDirSort(NSURL *leftURL, NSURL *rightURL, void *ptr)
{
(void)ptr;
NSDate * dateLeft ;
[leftURL getResourceValue:&dateLeft
forKey:NSURLContentModificationDateKey
error:nil] ;
NSDate * dateRight ;
[rightURL getResourceValue:&dateRight
forKey:NSURLContentModificationDateKey
error:nil] ;
return [dateLeft compare:dateRight];
}
- (NSArray *)contentsOrderedByDateOfDirectoryAtPath:(NSURL *)URLOfFolder ;
{
NSArray *files = [self contentsOfDirectoryAtURL:URLOfFolder
includingPropertiesForKeys:[NSArray arrayWithObject:NSURLContentModificationDateKey]
options:0
error:nil];
return [files sortedArrayUsingFunction:contentsOfDirSort
context:nil] ;
}