title: UIWebView or WKWebkit for JavaScript?
body: <p>I am wanting to load a requested webpage and accessing elements of the DOM to return a value from one of the nodes. I have some JavaScript that does this. Question is which is best method to return the value to my app. 
   I see UIWebView has a function </p>
  
  <p>stringByEvaluatingJavaScriptFromString </p>
  
  <p>and WKWebKit has function </p>
  
  <p>func evaluateJavaScript(javaScriptString: String!, completionHandler: ((AnyObject!, NSError!) -> Void)!)</p>
  
  <p>Well what's the main difference between them and which is better and why for my use case? </p>