Get directory contents in date modified order

问题:

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.

回答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;                                                             }]; 

回答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];                         }];

回答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]; }];

回答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; }

回答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; }

`

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