Converting URL to String and back again

So I have converted an NSURL to a String. So if I println it looks like file:///Users/... etc.

Later I want this back as an NSURL so I try and convert it back as seen below, but I lose two of the forward slashes that appear in the string version above, that in turn breaks the code as the url is invalid.

Why is my conversion back to NSURL removing two forward slashes from the String I give it, and how can I convert back to the NSURL containing three forward slashes?

var urlstring: String = recordingsDictionaryArray[selectedRow]["path"] as String
println("the url string = \(urlstring)")
// looks like file:///Users/........etc
var url = NSURL.fileURLWithPath(urlstring)
println("the url = \(url!)")
// looks like file:/Users/......etc

In Swift 5, Swift 4 and Swift 3 To convert String to URL:

URL(string: String)

or,

URL.init(string: "yourURLString")

And to convert URL to String:

URL.absoluteString

The one below converts the 'contents' of the url to string

String(contentsOf: URL)

fileURLWithPath() is used to convert a plain file path (e.g. "/path/to/file") to an URL. Your urlString is a full URL string including the scheme, so you should use

let url = NSURL(string: urlstring)

to convert it back to NSURL. Example:

let urlstring = "file:///Users/Me/Desktop/Doc.txt"
let url = NSURL(string: urlstring)
println("the url = \(url!)")
// the url = file:///Users/Me/Desktop/Doc.txt

There is a nicer way of getting the string version of the path from the NSURL in Swift:

let path:String = url.path

NOTICE: pay attention to the url, it's optional and it can be nil. You can wrap your url in the quote to convert it to a string. You can test it in the playground.
Update for Swift 5, Xcode 11:

import Foundation

let urlString = "http://ifconfig.me"
// string to url
let url = URL(string: urlString)
//url to string
let string = "\(url)"
// if you want the path without `file` schema
// let string = url.path

2021 | SWIFT 5.1:

From STRING to URL:

//ver 1 - better to use it for http/https
//BUT DO NOT use for local paths
let url = URL(string:"https://stackoverflow.com/")

//ver 2 -- for local paths
let url1 = URL(fileURLWithPath: "//Users/Me/Desktop/Doc.txt")
let url2 = URL(fileURLWithPath: "//Users/Me/Desktop", isDirectory: true)

// Possible solution, but better NEVER use it:
// Do not forget to add file:// in the beginning!!!!
let url3 = URL(string: "file:///Users/Me/Desktop/Doc.txt")!

From URL to STRING:

let a = String(describing: url)       // "file:////Users/Me/Desktop/Doc.txt"
let b = "\(url)"                      // "file:////Users/Me/Desktop/Doc.txt"
let c = url.absoluteString            // "file:////Users/Me/Desktop/Doc.txt"
let d = url.path                      // "/Users/Me/Desktop/Doc.txt" 

BUT value of d will be invisible due to debug process, so...

THE BEST SOLUTION for local files is:

let e = "\(url.path)"                 // "/Users/Me/Desktop/Doc.txt"

The best solution for network adresses is:

let c = url.absoluteString

Because of:

let url = URL(string: "https://stackoverflow.com/questions/27062454/converting-url-to-string-and-back-again")

print(url.path) // /questions/27062454/converting-url-to-string-and-back-again

let url = URL(string: "URLSTRING HERE")
let anyvar =  String(describing: url)

Swift 3 (forget about NSURL).

let fileName = "20-01-2017 22:47"
let folderString = "file:///var/mobile/someLongPath"

To make a URL out of a string:

let folder: URL? = Foundation.URL(string: folderString)
// Optional<URL>
//  ▿ some : file:///var/mobile/someLongPath

If we want to add the filename. Note, that appendingPathComponent() adds the percent encoding automatically:

let folderWithFilename: URL? = folder?.appendingPathComponent(fileName)
// Optional<URL>
//  ▿ some : file:///var/mobile/someLongPath/20-01-2017%2022:47

When we want to have String but without the root part (pay attention that percent encoding is removed automatically):

let folderWithFilename: String? = folderWithFilename.path
// ▿ Optional<String>
//  - some : "/var/mobile/someLongPath/20-01-2017 22:47"

If we want to keep the root part we do this (but mind the percent encoding - it is not removed):

let folderWithFilenameAbsoluteString: String? = folderWithFilenameURL.absoluteString
// ▿ Optional<String>
//  - some : "file:///var/mobile/someLongPath/20-01-2017%2022:47"

To manually add the percent encoding for a string:

let folderWithFilenameAndEncoding: String? = folderWithFilename.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed)
// ▿ Optional<String>
//  - some : "/var/mobile/someLongPath/20-01-2017%2022:47"

To remove the percent encoding:

let folderWithFilenameAbsoluteStringNoEncodig: String? = folderWithFilenameAbsoluteString.removingPercentEncoding
// ▿ Optional<String>
//  - some : "file:///var/mobile/someLongPath/20-01-2017 22:47"

The percent-encoding is important because URLs for network requests need them, while URLs to file system won't always work - it depends on the actual method that uses them. The caveat here is that they may be removed or added automatically, so better debug these conversions carefully.

Swift 3 version code:

let urlString = "file:///Users/Documents/Book/Note.txt"
let pathURL = URL(string: urlString)!
print("the url = " + pathURL.path)

Swift 5.

To convert a String to a URL:

let stringToURL = URL(string: "your-string")

To convert a URL to a String:

let urlToString = stringToURL?.absoluteString

>Swift 3 used with UIWebViewDelegate shouldStartLoadWith

  func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebViewNavigationType) -> Bool {

    let urlPath: String = (request.url?.absoluteString)!
    print(urlPath)
    if urlPath.characters.last == "#" {
        return false
    }else{
        return true
    }

}