CODEWITHSUNDEEP
objective-cmacosdirectory
Vince O'Sullivan
Vince O'Sullivan

Reputation: 2701

Objective-C - Finding directory size without iterating contents

I need to find the size of a directory (and its sub-directories). I can do this by iterating through the directory tree and summing up the file sizes etc. There are many examples on the internet but it's a somewhat tedious and slow process, particularly when looking at exceptionally large directory structures.

I notice that Apple's Finder application can instantly display a directory size for any given directory. This implies that the operating system is maintaining this information in real time. However, I've been unable to determine how to access this information. Does anyone know where this information is stored and if it can be retrieved by an Objective-C application?

Upvotes: 1

Views: 152

Answers (1)

uliwitness
uliwitness

Reputation: 8843

IIRC Finder iterates too. In the old days, it used to use FSGetCatalogInfo (an old File Manager call) to do this quickly. I think there's a newer POSIX call for that these days that's the fastest, lowest-level API for this, especially if you're not interested in all the other info besides the size and really need blazing speed over easily maintainable code.

That said, if it is cached somewhere in a publicly accessible place, it is probably Spotlight. Have you checked whether the spotlight info for a folder includes its size?

PS - One important thing to remember when determining the size of a file: Mac files can have two "forks", the data fork, and the resource fork (where e.g. Finder keeps the info if you override a particular file to open with another application than the default for its file type, and custom icons assigned to files). So make sure you add up both forks' sizes, or your measurements will be off.

Upvotes: 1

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