title: Expression type "(_, _) -> Void" is ambiguous without more context
body: <p>Please help me in below code. I'm getting an error:</p>
  
  <blockquote>
    <p>Expression type "(_, _) -> Void" is ambiguous without more context.</p>
  </blockquote>
  
  <pre><code>import UIKit
  import SDWebImage
  
  class CustomImageView: UIImageView {
      let progressIndicatorView = CircularLoaderView(frame: CGRect.zero)
  
      required init(coder aDecoder: NSCoder) {
          super.init(coder: aDecoder)!
  
          addSubview(self.progressIndicatorView)
          progressIndicatorView.frame = bounds
          progressIndicatorView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
  
          let url = NSURL(string: "http://png-3.findicons.com/files/icons/2795/office_2013_hd/2000/word.png")
          self.sd_setImage(with: url as URL?, placeholderImage: nil, options: .cacheMemoryOnly, progress: { [weak self] (receivedSize, expectedSize) -&gt; Void in
              self.progressIndicatorView.progress = CGFloat(receivedSize)/CGFloat(expectedSize)
          }) { [weak self](image, error, _, _) -&gt; Void in
              self.progressIndicatorView.reveal()
          }
      }
  }
  </code></pre>