Setting default save location for NSSavePanel

I'm trying to configure my NSSavePanel instance to have the default 'where' location be set to the user's Desktop, as opposed to the Documents folder, which is what it is currently. I tried to modify my code based on this accepted SO answer. However, the default 'where' location is still the Documents folder. Can someone tell me what I'm doing wrong?

- (void)saveFile:(NSString *)path extension:(NSString *)extension
{
    // Build a save dialog
    self.savePanel = [NSSavePanel savePanel];
    self.savePanel.allowedFileTypes = @[ extension ];
    self.savePanel.allowsOtherFileTypes = NO;

    // Hide this window
    [self.window orderOut:self];

    [self.savePanel setDirectoryURL:[NSURL URLWithString:@"/Users/user/desktop"]];

    // Run the save dialog
    NSInteger result = [self.savePanel runModal];
    if (result == NSFileHandlingPanelOKButton) {
        // Build the URLs
        NSURL *sourceURL = [NSURL fileURLWithPath:path];
        NSURL *destinationURL = self.savePanel.URL;

        // Delete any existing file
        NSFileManager *fileManager = [NSFileManager defaultManager];
        NSError *error = nil;

        if ([fileManager fileExistsAtPath:destinationURL.path]) {
            [fileManager removeItemAtURL:destinationURL error:&error];

            if (error != nil) {
                [[NSAlert alertWithError:error] runModal];
            }
        }

        // Bail on error
        if (error != nil) {
            return;
        }

        // Copy the file
        [[NSFileManager defaultManager] copyItemAtURL:sourceURL toURL:destinationURL error:&error];

        if (error != nil) {
            [[NSAlert alertWithError:error] runModal];
        }
    }

    // Cleanup
    self.savePanel = nil;
}

Instead of:

[self.savePanel setDirectoryURL:[NSURL URLWithString:@"/Users/user/desktop"]];

Try doing:

[self.savePanel setDirectoryURL:[NSURL fileURLWithPath:@"/Users/user/desktop"]];

making certain to replace user with the correct user name.