customURL.m

Here is what you need to do to register your app for a custom URL scheme (for the example we will use a "myapp" scheme).

1) In your Info.plist, add a new entry for CFBundleURLTypes: 

<key>CFBundleURLTypes</key> 
<array> 
  <dict> 
    <key>CFBundleURLName</key> 
    <string>MyApp's URL</string> 
    <key>CFBundleURLSchemes</key> 
    <array> 
      <string>myapp</string> 
    </array> 
  </dict> 
</array>

2) Somewhere in your application's startup code (e.g. init), add this code: 

- (void)registerMyApp { 
  [[NSAppleEventManager sharedAppleEventManager] setEventHandler:self andSelector:@selector(getUrl:withReplyEvent:) forEventClass:kInternetEventClass andEventID:kAEGetURL]; 
}

- (void)getUrl:(NSAppleEventDescriptor )event withReplyEvent:(NSAppleEventDescriptor )replyEvent { 
  NSString url = [[event paramDescriptorForKeyword:keyDirectObject] stringValue]; // Now you can parse the URL and perform whatever action is needed 
}


Related Tidbits:


In Mac OS X Tiger and later, you can call LSSetDefaultHandlerForURLScheme to register an app as the default handler for a protocol, as would be need for a common protocol such as http, or ftp.