I’m working on implementation of unimplemented properties in NSURL.swift.
public var filePathURL: NSURL?
As per specification which says " If the receiver is a file reference URL, this property contains a copy of the URL converted to a file path URL. If the receiver’s URL is a file
path URL, this property contains the original URL. If the original URL is not a file URL, or if the resource is not reachable or no longer exists, this property contains
‘filePathURL’ property is to hold copy of file reference URL converted to file path URL.
file reference URL - file:///.file/id=6571367.3617528/
file path URL - file:///Users/mbvreddy/workarea/swift/MyTest/MyTest.xcodeproj/
File reference URL is a special URL on OS X which is of type file:///.file/id=<volume_id>.<file_id>/ .
And it is not available on Linux. APIs that return file reference URLs  on OS X foundation NSURL.fileReferenceURL() is removed from Linux Foundation.
So, I think NSURL.filePathURL also should be removed as it serves no purpose without file reference URL. Any comments are appreciated.