title: Value of type 'UIImageView' has no member 'kf' in swift 4
body: <p>I am using Kingfisher library for downloading an image from URL and setting to UIIMageView in Swift 4 project.</p>
  
  <p>I know there are API changes between Kingfisher 2 and Kingfisher 3 </p>
  
  <p><a href="https://github.com/onevcat/Kingfisher/wiki/Kingfisher-3.0-Migration-Guide" rel="nofollow noreferrer">https://github.com/onevcat/Kingfisher/wiki/Kingfisher-3.0-Migration-Guide</a></p>
  
  <p>My project was working a few weeks back but after upgrading Xcode, cannot compile the project. It gives error </p>
  
  <p><a href="https://i.stack.imgur.com/kPddm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kPddm.png" alt="enter image description here"></a></p>
  
  <p>I have tried deleting derived data and all possible solutions from the links I have got it from google.</p>
  
  <p>Anyone facing the same issue with Kingfisher library? </p>
  
  <p><strong>Note: I have manually added Kingfisher library in the project. Not by pod or other package managers.</strong></p>