let url = URL(string: item)! returning nil in swift

Really cannot figure this one out, the URL prints and is not equal to nil, and it works in the browser when I paste it in. Any ideas?

import UIKit

class WebViewController: UIViewController {

    var postLink: String = String()
    @IBOutlet weak var mywebView: UIWebView!

    override func viewDidLoad() {
        super.viewDidLoad()
        print(postLink)

        let attempt = postLink
        let url: URL = URL(string: attempt)!
        let request: URLRequest = URLRequest(url: url)
        mywebView.loadRequest(request)

    }

The error occurs at:

let url: URL = URL(string: attempt)!