title: Replace double quote(") with escape double quote(\") is not working in iOS 11
body: <p>I am trying to replace double quote (") with escape double quote(\"), but it is unable to replace in iOS 11. Same works fine till iOS 10. I am using Xcode 9.1.</p>
  
  <p>Example:</p>
  
  <p>Input from search bar : "Course" </p>
  
  <pre><code>NSString *modifedSearchString = [searchBar.text stringByReplacingOccurrencesOfString:@"\"" withString:@"\\""\""];
  </code></pre>
  
  <p>Expected Output : \"Course\" (Working this till iOS 10)</p>
  
  <p>O/p in iOS 11 : "Course"</p>
  
  <p>Anyone facing same issue?</p>
  
  <p>Thanks in advance!!</p>