How can I calculate the size of a folder?

Cheers for that Alex, you helped a lot, have now written the following function which does the trick...

- (unsigned long long int)folderSize:(NSString *)folderPath {
    NSArray *filesArray = [[NSFileManager defaultManager] subpathsOfDirectoryAtPath:folderPath error:nil];
    NSEnumerator *filesEnumerator = [filesArray objectEnumerator];
    NSString *fileName;
    unsigned long long int fileSize = 0;

    while (fileName = [filesEnumerator nextObject]) {
        NSDictionary *fileDictionary = [[NSFileManager defaultManager] fileAttributesAtPath:[folderPath stringByAppendingPathComponent:fileName] traverseLink:YES];
        fileSize += [fileDictionary fileSize];
    }

    return fileSize;
}

It is coming up with the exact number of bytes as Finder does.

As an aside, Finder returns two numbers. One is the size on the disk and the other is the actual number of bytes.

For example, when I run this code on one of my folders, it comes back in the code with a 'fileSize' of 130398. When I check in Finder, it says the size is 201KB on disk (130,398 bytes).

Am a little unsure of what to go with here (201KB or 130,398 bytes) as the actual size. For now, I'll go on the safe side and cut my limit in half until I find out what this means exactly...

If anyone can add any more information to these differing numbers I'd appreciate it.

Cheers,

if we want to get the size of any file then here is a method, where we only need to pass path of that file.

- (unsigned long long int) fileSizeAt:(NSString *)path {
    NSFileManager *_manager = [NSFileManager defaultManager];
    return [[_manager fileAttributesAtPath:path traverseLink:YES] fileSize];
}

Not sure if this helps anyone, but I wanted to relate some of my findings (some inspired by @zneak's comment above).

1. I could not find any shortcuts using NSDirectoryEnumerator to avoid enumerating through files to get the total contained size of a directory.

2. For my tests, using -[NSFileManager subpathsOfDirectoryAtPath:path error:nil] was faster than using -[NSFileManager enumeratorAtPath:path]. This looks to me like it might be a classic time/space tradeoff, as subPaths... creates an NSArray on which it then iterates, where enumerator... might not.

Some background on #1. Assuming:

NSFileManager *fileMan = [NSFileManager defaultManager];
NSString *dirPath = @"/"; // references some directory

Then

[fileMan enumeratorAtPath:dirPath] fileAttributes]

returns nil. The correct attribute accessor is directoryAttributes, but

[fileMan enumeratorAtPath:dirPath] directoryAttributes] fileSize]

returns the size of the directory information, not the recursive sum of the sizes of all contained files (a lá ⌘-I in Finder).