What is a “delegate” in Objective C's iPhone development? [duplicate]

Answer 1

I think this Wikipedia article describes it best: http://en.wikipedia.org/wiki/Delegation_pattern

It is "just" an implementation of a design pattern and very common in Objective-C

Answer 2

Delegate is nothing but instance of Object which we can call methods behalf of that Objects. and also helps to create methods in rumtime of that Objects.

Answer 3

See this discussion

A delegate allows one object to send messages to another object when an event happens. For example, if you're downloading data from a web site asynchronously using the NSURLConnection class. NSURLConnection has three common delegates:

 - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
 - (void)connectionDidFinishLoading:(NSURLConnection *)connection
 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

One or more of these delegates will get called when NSURLConnection encounters a failure, finishes successfully, or received a response from the web site, respectively.

Answer 4

Delegates are a design pattern; there is no special syntax or language support.

A delegate is just an object that another object sends messages to when certain things happen, so that the delegate can handle app-specific details the original object wasn't designed for. It's a way of customizing behavior without subclassing.