[ios] How to convert this var string to URL in Swift

I need url filepath be a URL (NSURL in old versions of Swift). I have this:

let paths = NSSearchPathForDirectoriesInDomains(
        .documentDirectory, .userDomainMask, true)

// NSString *documentsDirectory = [paths objectAtIndex:0];
let documentsDirectory = paths[0] as String

var filePath:String? = nil
var fileNamePostfix = 0
repeat {
    filePath =
    "\(documentsDirectory)/\(dateTimePrefix)-\(fileNamePostfix).mp4"
    fileNamePostfix += 1
} while (FileManager.default.fileExists(atPath: filePath))

I need to convert this to URL for use in self.fileOutput.startRecording(to: <#outputFileURL: URL?#>, recordingDelegate: <#AVCaptureFileOutputRecordingDelegate?#>) method.

I tried filePath as? URL() but it isn't correct.

in swift 4 to convert to url use URL

let fileUrl = URL.init(fileURLWithPath: filePath)

or

let fileUrl = URL(fileURLWithPath: filePath)

To Convert file path in String to NSURL, observe the following code

var filePathUrl = NSURL.fileURLWithPath(path)

In Swift3:
let fileUrl = Foundation.URL(string: filePath)

In swift 3 use:

let url = URL(string: "Whatever url you have(eg: https://google.com)")