What is a registered prefix?

What is a regist开发者_开发问答ered prefix that has to be done before the url to be called in Objective-C programming of iPhone OS?

Can you explain this to me with an example?

For searching purposes, what you describe is usually called a "custom URL scheme". That search gives many tutorials and code examples.

Apple have a sample project that demonstrates registering for a URL called LaunchMe.

The important part is to register for the custom URL by modifying your project plist (as per the linked tutorials), and then act to upon being called via that URL via the delegate method:

- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url