Now that you’ve seen an iOS app in action, you might be wondering what keeps your app “alive,” so to speak. In the Shorty app, you created action methods that were called when the user tapped on a button or the Go key on the keyboard. You created delegate objects that received messages when certain milestones were reached, like when a web page had problems loading or the URL shortening service responded. You never wrote any code to see if the user had touched something or checked to see if the web page had finished loading. In other words, you didn’t go out and get this information; your app waited for this information to come to it.