title: Copy images from an app to Documents Directory and rewrite them after it
body: <p>I have an app where I have a certain amount of .jpg pictures (roughly 300). They serve as something to start with, because they're actually located in the internet, but obviously it's more convenient for user not to download all of them at the first start of the App, but to have them pre-packed.</p>
  
  <p>I am required to rewrite these images everytime I get new information from server. Obviously, I can't touch the app bundle, so I see my steps like this:</p>
  
  <ol>
  <li>Unpack the images from bundle to the Documents Directory at the first start of an App.</li>
  <li>Access them only from Documents Directory, but not from bundle.</li>
  <li>If it's necessary, I should rewrite them.</li>
  </ol>
  
  <p>And thus my code will be unified, cause I will always use the same path to get the image.</p>
  
  <p>The problem is that I know very little about the whole file system thing in iOS, so I don't know how to unpack the particular bundle contents to Documents Directory and also I don't know how to write to Documents Directory either.</p>
  
  <p>Could you please help me with some code and also confirm that my solution scheme is right?</p>