I am coming from the C#/.NET world and have two questions for you more experienced Objective C aficionados!
The code at the top of page 85 confuses me for the following reason: The code pertains to CLLocationManager implementing a method that is checking (using respondsToSelector:) to see if another method is implemented by CLLocationManager. Why would CLLocationManager NOT know what other methods it implements? …I can understand the WhereamiAppDelegate class not knowing what CLLocationManager implements, but why does CLLocationManager need to use the respondsToSelector: to see what other methods it implements?
Also, the last paragraph on page 84 starts off with “Before sending an optional method,”. Should this read “Before sending an optional message”?