title: custom button with image for FBSDKLoginButton
body: <p>i want use a custom button with image ,</p>
  
  <p>I don't want to use Facebook default login button.</p>
  
  <p>this is my code </p>
  
  <pre><code>    let loginButton = FBSDKLoginButton()
      loginButton.readPermissions = ["public_profile", "email", "user_friends"]
      loginButton.center = self.view.center
      loginButton.delegate = self
      loginButton.imageView?.image = UIImage(named: "cyanx2")
      self.view.addSubview(loginButton)
  </code></pre>
  
  <p>and my button would be </p>
  
  <pre><code>@IBAction func customButton(sender: UIButton) {
  
   // here's go the action when click on default facebook button   
  }
  </code></pre>