title: How to use NSOperation & NSOperationQueue in Objective-C?
body: <p>I am developing a custom camera application.What I am doing is , I am taking picture using camera and showing them in same VC bottom of the screen.</p>
  
  <p>I am storing the image in local dictionaries and NSDocument directory path. If the picture is in local dictionaries it will take from local dictionary else it will take from the NSDocument directory path.</p>
  
  <p>After memory warning received, I just nil the dictionary ,so it will take the images from the NSDocument directory path.</p>
  
  <p>Using both will showing images in  slow process.My UI got not that much good in showing images.</p>
  
  <p>So I want to store the images in NSDocument directory path using NSOperation.</p>
  
  <p>I don't have much knowledge about NSOperation. I have searched in google , I am just getting swift tutorials while I require help in Objective C.</p>
  
  <p>So please can anyone explain the <code>NSOperation</code> and <code>NSOperationQueue</code> with examples?</p>