What is the purpose of an iOS delegate?

Question

I understand what a delegate does in iOS, and I\'ve looked at sample code, but I\'m just wondering about the advantages of this type of encapsulation (as opposed to includin

Answer 1

In iOS ecosystem especially UIKit Framework which consists of UIApplication, UITableView, UICollectionView, UITextfield & so on uses delegate & datasource design pattern intensively to communicate data to and fro.

Delegate design pattern is used to pass/communicate data from FirstVC(Delegator) to SecondVC(Delegate) to complete a task. Here, SecondVC(Delegate) conforms to a protocol delegate & implements all its requirements like methods by providing body to complete that task given by FirstVC(Delegator). Also, FirstVC(Delegator) object will be having a optional property of protocol delegate type i.e delegate which must be assigned by SecondVC(Delegate).

Now, FirstVC(Delegator) can call that method residing in SecondVC(Delegate) by passing data from its delegate property.

EX: CEO(FirstVC) which passes data i.e "confidential data" to Secretary(SecondVC) to do further processes using that data.

Datasource design pattern is part of Delegate pattern which is used to pass/communicate data from SecondVC(Delegate) to FirstVC(Delegator) when a task is assigned to SecondVC(Delegate). Here, SecondVC(Delegate) conforms to a protocol datasource & implements all its requirements like methods with return type by providing body to talk back to FirstVC(Delegator) after the task is given by FirstVC(Delegator). Also, FirstVC(Delegator) object will be having an optional property of protocol dataSource type i.e dataSource which must be assigned by SecondVC(Delegate).

Now, FirstVC(Delegator) can call that method with a return type residing in SecondVC(Delegate) by passing data from its dataSource property.

EX: Secretary(SecondVC) replies back with a data i.e "Sir, I am already having too much work to do. Please, can you assign that data to others" to CEO(FirstVC). Now, CEO(FirstVC) will analyse that data to do further processes.