oop

Question 1

Properties

Answer 1

You declare the instrument’s stored properties (data) that all instruments have. In this case, it’s just the brand, which you represent as a String.

You create an initializer for the class with the init keyword. Its purpose is to construct new instruments by initializing all stored properties.

Question 2

Methods

Answer 2

Functions defined inside a class are called methods because they have access to properties, such as brand in the case of Instrument. Organizing properties and related operations in a class is a powerful tool for taming complexity. It even has a fancy name: encapsulation. Class types are said to encapsulate data (e.g. stored properties) and behavior (e.g. methods).

Question 3

Inheritance

Answer 3

You create the Piano class as a subclass of the Instrument parent class. All the stored properties and methods are automatically inherited by the Piano child class and available for use.

Question 4

Polymorphism

Answer 4

Polymorphism
One of the great strengths of object oriented programming is the ability to use different objects through the same interface while each behaves in its own unique way. This is polymorphism meaning “many forms”

Polymorphism means “having multiple forms”. Objects of different classes can be used interchangeably if they have a common superclass.

Question 5

Encapsulation

Answer 5

Encapsulation

means that objects keep their state information private. Rather than directly manipulating an object’s data, other objects send requests to the object, in the form of messages, some of which the object may respond to by altering its internal state

Question 6

Protocols

Answer 6

A protocol defines a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. The protocol can then be adopted by a class, structure, or enumeration to provide an actual implementation of those requirements. Any type that satisfies the requirements of a protocol is said to conform to that protocol.

Question 7

Delegation

Answer 7

One of the most overused design pattern in iOS is delegation. A class can delegate a part of it’s responsibilities to an instance of another class. This design pattern is implemented by defining a protocol that encapsulates the delegated responsibilities, such that a conforming type (known as a delegate) is guaranteed to provide the functionality that has been delegated.