title: How can I add loading view at Launching time?
body: <p>I'm using storyboard to develop my app, and the initial view controller is a Tab Bar Controller. At the AppDelegate I did some thing work to get the jsonData from my website. It will take 10-20 seconds . You know, I want to do something to notice user is loading, not just showing a default.png picture. How can I do it?</p>