title: How to catch the event when a view is shown after returning from another view?
body: <p>A simple question I just can't find the answer...</p>
  
  <p>I have view A and B, after clicking on a button on A, B shows up, and at this time if I click the back button on device, A will be shown again. Now I change something in B and hope it would affect A, e.g. setting A's background color via a global variable, so that when the back button is pressed, A's background color changes, how could I do this? What method is fired when A is shown from clicking the back button?</p>