Why use delegation? Well when writing Objective-C programs in Xcode we are encouraged to use the MVC(Model View Controller) structure.In MVC a model cannot send messages directly to a specific controller.This can become a problem if data in your model changes independantly and you need to update this information in your view via the controller(The model must never communicate directly with the view).This is where a delegate comes in,it allows messages to be sent from the model to a controller that is not specified in the model but is rather specified by the controller,in other words the controller specifies itself. If you dont really understand what im talking about so far ,don't worry.I didn't understand delegates either until I needed one,but hopefully by the end of this tutorial you will understand not only how to use a delegate ,but the reason you would want to use one. Program breakdown For this tutorial we will write a program that has a model that will change an...