Equatable, Hashable, Comparable protocols in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Equatable protocol do in Swift?

The Equatable protocol allows you to check if two values are equal using the == operator. It helps compare if two instances are the same.

beginner

Why is the Hashable protocol important?

The Hashable protocol lets a type be used in collections like Set or as keys in Dictionary. It provides a way to create a hash value for each instance.

beginner

What does the Comparable protocol allow you to do?

The Comparable protocol lets you compare values to see which is smaller, equal, or larger using operators like <, <=, >, and >=. It helps sort values.

intermediate

How do you make a custom Swift struct conform to Equatable?

You add Equatable to the struct declaration. Swift can automatically create the == function if all properties are Equatable. Example: <br>struct Point: Equatable { var x: Int; var y: Int }

intermediate

What must you implement when conforming to Hashable?

You must provide a hash(into:) method that feeds the essential properties into the hasher. This creates a hash value for the instance.

Which operator is required by the Equatable protocol?

A ==

B +

C <

D !=

The Equatable protocol requires the == operator to check equality.

What does conforming to Hashable enable for a type?

A Use in sets and dictionary keys

B Automatic sorting

C Printing to console

D Inheritance from other classes

Conforming to Hashable allows a type to be stored in sets and used as dictionary keys.

Which protocol lets you compare if one value is less than another?

A Equatable

B Hashable

C Codable

D Comparable

Comparable provides operators like < to compare values.

If a struct has only Equatable properties, what happens when you add Equatable conformance?

A You must write the <code>==</code> function manually

B Swift automatically generates the <code>==</code> function

C The struct cannot conform to Equatable

D You must implement <code>hash(into:)</code>

Swift can automatically create the == function if all properties are Equatable.

What method must you implement for Hashable conformance?

A func equals()

B func compare(to other: Self)

C func hash(into hasher: inout Hasher)

D func encode()

You must implement hash(into:) to provide a hash value.

Explain the purpose of the Equatable, Hashable, and Comparable protocols in Swift and how they differ.

Think about equality, uniqueness, and order.

Describe how you would make a custom struct conform to Equatable and Hashable in Swift.

Focus on protocol conformance and required methods.