1)What is property?

Using properties we can access the object as a global variable.

2)What is delegate?

Delegate is a design pattern. We can send the message from one class to another class using delegates.

3)What is notification center?

We can send the message from one class to multiple classes using notification center. It acts like a broadcasting system.

4)What is category?

We can add the methods to an existing classes using category. For example we can add our own custom methods to NSString class using category.

5)What is extension?

It is also same as extension we can add methods to an existing classes which having source code. For categories source code is not required.

6)What are the different types of protocols?

  • Formal protocols
  • Informal protocols

7)What is formal protocol?

Formal protocols are nothing but an extensions in objective-c.

8)What is informal protocols?

Informal protocols are nothing but a categories in objective-c.

9)What is accessor methods in objective-c?

Accessor methods are nothing but a setters and getter methods in objectiv- c.

10)What is setter method?

Using setter methods we can set the value to the objects.

11)What is getter method?

Using getter methods we can get the value from the object.