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Question

How do you find how much disk space is left in Cocoa?

Answer 1

+6 A:

-[NSFileManager attributesOfFileSystemForPath:error:]

Azeem.Butt 2009-10-26 18:09:38

-[NSFileManager attributesOfFileSystemForPath:error:] doesn't return a dict with the key NSFileSystemFreeSize in it.

zekel 2009-10-28 21:26:48

Whoops, you were right. Looks like I tried that on the class, not the instance.

zekel 2010-01-20 22:06:12

Answer 2

+2 A:

EDIT fileSystemAttributesAtPath: is deprecated, use attributesOfFileSystemForPath:error: as NSD suggested. I made a mistake when I thought it didn't work.

// this works
NSError *error = nil;
NSDictionary *attr = [NSFM attributesOfFileSystemForPath:@"/" error:&error];
if (!error) {
    double bytesFree = [[attr objectForKey:NSFileSystemFreeSize] doubleValue];
}

I tried this, attributesOfItemAtPath:error but the dict returned didn't seem to have the NSFileSystemFreeNodes key.

NSFileManager *fm = [NSFileManager defaultManager];
NSError *error = nil;
NSDictionary *attr = [fm attributesOfItemAtPath:@"/" error:&error];
if (!error) {
    NSLog(@"Attr: %@", attr);
}

2009-10-28 17:21:11.936 MyApp[33149:a0b] Attr: {
    NSFileCreationDate = "2009-08-28 15:37:03 -0400";
    NSFileExtensionHidden = 0;
    NSFileGroupOwnerAccountID = 80;
    NSFileGroupOwnerAccountName = admin;
    NSFileModificationDate = "2009-10-28 15:22:15 -0400";
    NSFileOwnerAccountID = 0;
    NSFileOwnerAccountName = root;
    NSFilePosixPermissions = 1021;
    NSFileReferenceCount = 40;
    NSFileSize = 1428;
    NSFileSystemFileNumber = 2;
    NSFileSystemNumber = 234881026;
    NSFileType = NSFileTypeDirectory;
}

After looking around a bit, it seems like fileSystemAttributesAtPath: is the method that returns it. Weird.

NSFileManager *fm = [NSFileManager defaultManager];
NSDictionary *attr = [fm fileSystemAttributesAtPath:@"/"]; 
NSLog(@"Attr: %@", attr);


2009-10-28 17:24:07.993 MyApp[33283:a0b] Attr: {
    NSFileSystemFreeNodes = 5027061;
    NSFileSystemFreeSize = 20590841856;
    NSFileSystemNodes = 69697534;
    NSFileSystemNumber = 234881026;
    NSFileSystemSize = 285481107456;
}

zekel 2009-10-28 21:27:59

“… use attributesOfFileSystemForPath:error: instead.” That's what NSD suggested, and you told him it didn't work. Does it work now?

Peter Hosey 2010-01-20 20:47:18

Yeah, it does. Looks like I made a mistake before.

zekel 2010-01-20 22:09:11

Two critiques: `error:` parameters take a pointer to a pointer to an object, `NSError **`. Thus, the correct null pointer constant is not `nil` (which would be a pointer to an object, either `<class-name> *` or `id`), it's `NULL`. More importantly, don't suppress the error return—pass a pointer to a variable there, and report the error if (and only if) the attempt to retrieve attributes fails. Silent failure is bad.

Peter Hosey 2010-01-21 02:11:05

You're right on both counts. Added better handling to example code to be more instructive.

zekel 2010-10-28 18:04:57

Answer 3

+1 A:

I use this:

NSDictionary* fileAttributes = [[NSFileManager defaultManager] attributesOfFileSystemForPath:@"/"
                                                                                   error:&error];
unsigned long long freeSpace = [[fileAttributes objectForKey:NSFileSystemFreeSize] longLongValue];
NSLog(@"free disk space: %dGB", (int)(freeSpace / 1073741824));

Avi Cohen 2010-04-15 14:23:26

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How do you find how much disk space is left in Cocoa?

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