Swift Subclassing and Extensions Quiz

This test assesses the understanding of subclassing, inheritance, and extensions in Swift, focusing on the fundamental concepts of object-oriented programming.

1.

What does inheritance allow in object-oriented programming?

To automatically generate documentation

To derive a new class from an existing class

To remove unwanted methods from a class

To create multiple instances of a class

2.

What is another name for a class from which a subclass is derived? (select all that apply)

Static class

Root class

Sibling class

Base class

3.

In Swift, how many direct parent classes can a subclass have?

One

Two

Unlimited

None

4.

What is the name of the class at the top of a class hierarchy?

Sibling class

Superclass

Root class

Parent class

5.

What would be the best way to create a savings account class based on an existing BankAccount class?

Duplicate the BankAccount class

Extend the BankAccount class using a function

Derive a new class from the BankAccount class

Create a completely new class from scratch

6.

In Swift, which of the following is used to indicate a subclass?

:

extends

override

sub

7.

What does the override keyword do in Swift?

It indicates that a method in a subclass replaces a method from the superclass

It automatically generates a new method

It prevents a method from being called

It deletes a method from the superclass

8.

When overriding a method, what must be true about the parameters and return type?

They must be different from the superclass

They must be similar in concept but not in structure

They must exactly match the superclass method

They must use optional types

9.

Why might you override a method rather than creating a new one in a subclass?

To modify the behavior of an inherited method

To prevent inheritance

To save memory

To keep method names consistent

10.

How can a subclass method call the method it overrides in the superclass?

By calling super.methodName()

By using the base keyword

By creating an extension

By directly invoking it with its name

11.

When must the init method of the superclass be called during subclass initialization?

After subclass properties are initialized

Only if needed

It is optional

At the beginning

12.

What is the primary difference between subclassing and extensions in Swift?

Extensions require additional memory allocation

Subclasses are always faster

Subclasses can be created without a parent class

Extensions cannot override methods or add stored properties

13.

What can extensions in Swift be used to add to existing classes?

Methods, initializers, computed properties, and subscripts

Methods and static properties only

Only methods

Only stored properties

14.

How are extensions declared in Swift?

subclass ClassName { }

extend { }

extension ClassName { }

extend ClassName { }

15.

What advantage do extensions have over subclassing?

Extensions allow methods overrides

Extensions can replace stored properties

Extensions are faster than subclasses

Extensions add functionality without creating a new class

16.

Which of the following is true about extensions in Swift?

Extensions are limited to built-in classes only

Extensions can be used to override methods

Extensions can contain stored properties

Extensions can be used to add computed properties

17.

Which example shows a valid use of extensions?

Overriding a method in a class

Adding a parent class

Adding stored properties to a class

Adding a computed property to a class

18.

Which of the following statements about Swift extensions is true?

Extensions can modify the behavior of existing stored properties

Extensions require subclasses to work

Extensions provide additional functionality without altering existing behavior

Extensions are more powerful than subclassing

19.

How does single inheritance in Swift influence class design?

It simplifies the inheritance structure by allowing only one parent class

It limits the number of subclasses that can be created

It prevents the use of extensions

It forces each class to have multiple parent classes

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