"NSURL" is not implicitly convertible to "URL"; did you mean to use "as" to explicitly convert?

In swift 3 you need to use URL instead of NSURL, so create url object like this.

if let url = URL(string: "https://www.google.com") {
    webView.load(URLRequest(url: url))
}

Update for Swift 3.1:

let url = URL(string: "https://www.google.com")
let request = URLRequest(url: url!)
webView.load(request)

Notice the use of URL instead of NSURL and load instead of loadRequest.