title: UIImageView: full screen image
body: <p>I want to see a full screen image on the iPhone. how many 
  pixels I have to set it? width and height are different for iphone 3 and 
  4?</p>
  
  <p>My source code:</p>
  
  <pre><code>NSString *filePath = [[NSBundle mainBundle] pathForResource:theProduct.image ofType:@"png"]; 
  UIImageView *img = [[UIImageView alloc] initWithImage:[UIImage imageWithContentsOfFile:filePath]];
  img.frame = CGRectMake(0.0, 0.0, ?, ?);
  [self.view addSubview:img];
  </code></pre>
  
  <p>What should I put instead of question marks?</p>
  
  <p>Many thanks,
  Stefano</p>