Implementing Delegate Pattern in Objective-C

Question

I am building a class that handles NSURLConnection requests. To allow other classes to use this class, I would like to allow the main class to call a delegate when connecti

Answer 1

Since you tagged this with "iphone", I assume you're working on an iPhone app and don't need to support OS X pre-10.5. In Objective-C 2.0, Apple suggests you use formal protocols (using @protocol) with optional methods instead of informal protocols. Here's the relevant text:

Being informal, protocols declared in categories don’t receive much language support. There’s no type checking at compile time nor a check at runtime to see whether an object conforms to the protocol. To get these benefits, you must use a formal protocol. An informal protocol may be useful when all the methods are optional, such as for a delegate, but (on Mac OS X v10.5 and later) it is typically better to use a formal protocol with optional methods.

(source)