Get Volume UUID for Path

volumeUUIDForPath.swift

import DiskArbitration

func volumeUUIDForPath(path: String) -> String?
{
    var retval: String?
    
    if let session = DASessionCreate(kCFAllocatorDefault)
    {
        let fsStats = UnsafeMutablePointer<statfs>.alloc(1)
        defer { fsStats.destroy(1) }
        if statfs((path as NSString).UTF8String, fsStats) == 0
        {
            let deviceName = withUnsafePointer(&fsStats.memory.f_mntfromname,
            {
                (ptr) -> String? in
                let int8Ptr = unsafeBitCast(ptr, UnsafePointer<Int8>.self)
                return String.fromCString(int8Ptr)
            })
            
            if let device = deviceName,
                disk = DADiskCreateFromBSDName(kCFAllocatorDefault, session, device),
                description = DADiskCopyDescription(disk)
            {
                let myDict = description as NSDictionary
                let uuid = myDict[kDADiskDescriptionVolumeUUIDKey as String /* "DAVolumeUUIDD" */] as! CFUUID
                retval = CFUUIDCreateString(kCFAllocatorDefault, uuid) as String
            }
            else { retval = "" }
        }
    }
    
    return retval
}

I needed a way to get the volume UUID of a file in Swift. Given a path, it will return nil (the path isn't valid), an empty string (the path is probably on a network share) or the volume's UUID (as returned by "diskutil info").

Working at commit time on OS X 10.10.4, Swift 2.0, Xcode 7 beta 4.

This code was inspired by some of https://github.com/baron/polkit/blob/master/FileSystem/DiskWatcher.m