title: What is the alternative of [NSBundle mainBundle] URLForResource:withExtension: in iOS 3 SDK
body: <p>I am developing an iOS app using iOS 4.2 SDK, but I want the app to run on older devices like my iPhone 2G with iOS 3.1.3. I don't know what is the alternative for this code:</p>
  
  <pre><code>NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"CoreDataApp" withExtension:@"momd"];
  </code></pre>
  
  <p>It crashes on my device, because the URLForResource:withExtension: method is iOS 4+.</p>
  
  <p>Please help. Thanks.</p>