I am new to objective C. I want to ask why “delegate” is needed in objective C. Could you provide me specific reasons, situations and code examples for this. I appreciate if anyone could help.
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I am new to objective C. I want to ask why “delegate” is needed in objective C. Could you provide me specific reasons, situations and code examples for this. I appreciate if anyone could help.
This idiom is how what we might call “callbacks” in other languages are typically done in ObjC. A class needs to react to a given situation (let’s say a mouse click). The class is rather generic, and not coded with any domain-specific knowledge, so the policy for that action isn’t written by that class. Hence it needs to “delegate” that action to your code. So it calls a method on an object you specify. Since your code presumably knows what it wants to do when you click the mouse.
Apparently there’s even a Wikipedia article on this pattern, written by the kind of people who like to give special names to patterns. See: Delegation pattern.