I made sure that the results of allocatedSize are closer to the correct value by calculating the difference of the available bytes on the volume before and after deleting the test directory. The folderSize: method copied from some other answer calculates a total of 21 kB while my allocatedSize method yields 401 kB. In the test I create a directory containing 100 small files (ranging from 0 to 800 bytes). It shows how utterly wrong the results can be in some scenarios. I've also set up a simple iOS test project, demonstrating the differences between the solutions. The core of the solution is to use NSURL's NSURLTotalFileAllocatedSizeKey or NSURLFileAllocatedSizeKey properies to retrieve file sizes. It's also quite a bit faster, especially with directories containing a lot of files. So I'm proposing this extension on NSFileManager (code on github due to length: Swift 4, Objective C) to remedy the problem. HFS deploys file system compression to actually store the file using less bytes then its real length.Īll of these reasons make the existing answers produce unprecise results.Files carry around meta data (like any number of extended attributes).Even a one byte file uses at least one block. The space used on the volume increments in blocks, not in bytes.

This does not take a couple of subtleties into account. The existing answers all take a very simple approach: Traverse the directory contents, adding up the sizes of (regular) files. I'm aware that this definition is not the only valid way to interpret the question but I do think it's what most use cases boil down to.

It is the space becoming available if the directory would be completely removed. In my understanding (and probably the one of the OP) it is the amount of bytes that the directory including all of its contents uses on the volume.

To understand why we first have to define what the size of a folder is. I'd like to add my two cents to this old question as there seem to be many answers that are all very similar but yield results that are in some cases very unprecise.

Xyplorer calculate size directories