title: Why is there no forward button in the iPhone App?
body: <p>Why is there no forward button in the iPhone App?</p>
  
  <p>I'm in web industry over 5 years.</p>
  
  <p>recently, I dove into iPhone app.</p>
  
  <p>Some iPhone app developer told me 
  "It's very hard to add forward function into iPhone app. 
  And, back button implementation is not always possible although current screen is not the first screen of the app."</p>
  
  <p>Is it true?</p>
  
  <p>If true,
  why that is hard?
  why that is not always possible?</p>