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.

What does inheritance allow in object-oriented programming?

To create multiple instances of a class

To remove unwanted methods from a class

To automatically generate documentation

To derive a new class from an existing class

None

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

Root class

Sibling class

Static class

Base class

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

Two

None

One

Unlimited

None

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

Superclass

Parent class

Sibling class

Root class

None

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

Duplicate the BankAccount class

Create a completely new class from scratch

Extend the BankAccount class using a function

Derive a new class from the BankAccount class

None

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

sub

extends

override

None

What does the override keyword do in Swift?

It prevents a method from being called

It automatically generates a new method

It deletes a method from the superclass

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

None

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

They must use optional types

They must be different from the superclass

They must be similar in concept but not in structure

They must exactly match the superclass method

None

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

To save memory

To prevent inheritance

To modify the behavior of an inherited method

To keep method names consistent

None

10.

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

By directly invoking it with its name

By using the base keyword

By calling super.methodName()

By creating an extension

None

11.

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

Only if needed

At the beginning

After subclass properties are initialized

It is optional

None

12.

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

Extensions cannot override methods or add stored properties

Subclasses can be created without a parent class

Extensions require additional memory allocation

Subclasses are always faster

None

13.

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

Methods and static properties only

Only stored properties

Only methods

Methods, initializers, computed properties, and subscripts

None

14.

How are extensions declared in Swift?

extend ClassName { }

subclass ClassName { }

extend { }

extension ClassName { }

None

15.

What advantage do extensions have over subclassing?

Extensions are faster than subclasses

Extensions add functionality without creating a new class

Extensions can replace stored properties

Extensions allow methods overrides

None

16.

Which of the following is true about extensions in Swift?

Extensions can contain stored properties

Extensions can be used to add computed properties

Extensions can be used to override methods

Extensions are limited to built-in classes only

None

17.

Which example shows a valid use of extensions?

Adding a computed property to a class

Adding stored properties to a class

Adding a parent class

Overriding a method in a class

None

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 are more powerful than subclassing

Extensions provide additional functionality without altering existing behavior

None

19.

How does single inheritance in Swift influence class design?

It forces each class to have multiple parent classes

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

None

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