if let url = NSURL(string: "some url")
{
    if let req = NSURLRequest(URL: url)?
    {
        self.webView.loadRequest(req)
    }
}

Error emitted:

ViewController.swift:47:39: error: could not find an overload for 'init' that accepts the supplied arguments
    if let req = NSURLRequest(URL: url)?
                 ~~~~~~~~~~~~~~~~~~~~~~^