如何在iPhone中显示应用启动时滚动的介绍屏幕?

I have set the "Launch Images" in Xcode that shows a "Loading..." screen when the iPhone app is being launched. And now, once the app starts, I want to show a slide out animation programmatically with the same image to reveal the app content underneath - very similar to what Dropbox for iPhone does. What's the easiest way to do this?I have set the "Launch Images" in Xcode that sh