Getting alias path of file in swift

This is a solution using NSURL.

It expects an NSURL object as parameter and returns either the original path if the url is an alias or nil.

func resolveFinderAlias(url:NSURL) -> String? {

  var isAlias : AnyObject?
  do {
    try url.getResourceValue(&isAlias, forKey: NSURLIsAliasFileKey)
    if isAlias as! Bool {
      do {
        let original = try NSURL(byResolvingAliasFileAtURL: url, options: NSURLBookmarkResolutionOptions())
        return original.path!
      } catch let error as NSError {
        print(error)
      }
    }
  } catch _ {}

  return nil
}

Swift 3:

func resolveFinderAlias(at url: URL) -> String? {
    do {
        let resourceValues = try url.resourceValues(forKeys: [.isAliasFileKey])
        if resourceValues.isAliasFile! {
            let original = try URL(resolvingAliasFileAt: url)
            return original.path
        }
    } catch  {
        print(error)
    }
    return nil
}

Be aware to provide appropriate entitlements if the function is called in a sandboxed environment.