Swift-Native Method to Test If a Local NSURL is a File or a Directory

Posted 04/07/2016 8:33 PM by Corey Klass

As of this writing, NSFileManager unfortunately doesn't have a Swift-native way of determining if the object at an NSURL is a file or a directory. You can call the NSFileManager fileExistsAtPath:isDirectory: function, but the isDirectory parameter takes a reference to an Objective-C boolean, NOT a Swift-native boolean.

Extensions to the rescue! We can encapsulate our directory-testing logic into an NSFileManager extension that returns a Swift-native Bool value, so we don't have to play with any Objective-C in our code.

    //  NSFileManager+CKIsDirectory.swift

    import Foundation

    extension NSFileManager {

        func isDirectoryAtPath(url: NSURL) -> Bool {
            // we need an Objective-C boolean
            var isDirectory: ObjCBool = ObjCBool(false)

            // determine if this is a directory
            self.fileExistsAtPath(url.relativePath!, isDirectory: &isDirectory)

            // convert to a Swift Boolean
            let isDirectoryBool = Bool(isDirectory)

            // return the Swift boolean
            return isDirectoryBool