title: ios App improve network performance by requesting data up front
body: <p>I have an application that I'm writing that pulls data from a few network sources:
  1) list of blog posts (UITableViewController)
  2) list of videos (UIViewController with an embedded UIScrollView)
  3) list of images (UIViewController with an embedded UIScrollView)</p>
  
  <p>Right now, there is a home screen with a menu and when you push one of the buttons, a destinationViewController (described above) is what loads the data on demand. I've noticed this is quite slow, especially when on a cellular data connection as opposed to wifi.</p>
  
  <p>I was thinking about creating a class that requests all the data up front and kick it off every time the app is reentered. Does anyone have suggestions that could help me answer the following?</p>
  
  <p>1) are there any classes, frameworks, or existing i code i can use to kick off these requests in a single place?
  2) how do my destination view controllers (mentioned above) get the data?
  3) how do my destination view controllers get informed that the data is ready if they happen to be invoked before the data is available?
  4) is there a better strategy i should employ?</p>
  
  <p>I appreciate the help. </p>
  
  <p>Thanks,
  jas</p>