Run a background thread on Swift 3
<p>I have a function that goes like this:</p>

<pre><code>fileprivate func setupImageViewWithURL(url: URL) {
    var image: UIImage? = nil
    do {
        try image = UIImage(data: Data(contentsOf: url))!
    } catch is NSError {
        print("Failed")
    }

    image = self.imageWithImage(sourceImage: image!, scaledToWidth: UIScreen.main.bounds.size.width)
    self.imageImageView.image = image
    self.imageImageView.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: (image?.size.height)!)
}
</code></pre>

<p>I want to run it on a <code>Background</code> <code>thread</code>.</p>

<p>I've tried the <code>GDC</code> methods of <code>Swift2</code>, but it didn't work.</p>

<p>Did anything change in the thread topic in <code>Swift3</code>?</p>

<p>Thank you!</p>