iOS Programming: The Big Nerd Ranch Guide, Second Edition

Exceptions and the Console Window

In a language like C, we have functions, and when we call a function, code is executed. If we try and call a function that doesn’t exist, the compiler says, “I can’t do that, Joe,” and the code will fail to compile. This is known as a compile-time error.

Objective-C, being a dynamically typed language, isn’t able to figure out at compile time whether an object will respond to a message. (An object only responds to a message if its class implements the associated method.) The compiler will warn you if it thinks you are sending a message to an object that won’t respond, but the code will still compile. If, for some reason (and there are many), you end up sending a message to an object that doesn’t respond, your ...