Identity comparison (===) in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the identity operator === check in Swift?

It checks if two references point to the exact same instance of a class in memory.

beginner

How is === different from == in Swift?

=== checks if two variables refer to the same object instance, while == checks if two values are equal in content.

intermediate

Can === be used with structs or enums in Swift?

No, <code>===</code> only works with class instances because structs and enums are value types, not reference types.

beginner

Given two variables <code>a</code> and <code>b</code> of a class type, what does <code>a === b</code> return if they point to the same object?

It returns true because both variables reference the same instance in memory.

intermediate

Why is identity comparison useful in Swift programming?

It helps determine if two variables refer to the same object, which is important when managing shared resources or checking object uniqueness.

What does the === operator check in Swift?

A If two variables refer to the same class instance

B If two values are equal in content

C If two structs have the same properties

D If two enums have the same case

=== checks if two references point to the exact same object instance.

Can you use === to compare two structs in Swift?

A Yes, always

B Only if they are optional

C Only if they conform to Equatable

D No, because structs are value types

Structs are value types, so === which checks identity, cannot be used.

What will a === b return if a and b are different instances with the same content?

A false

B true

C It causes a compile error

D Depends on the class

=== returns false because the instances are different, even if content matches.

Which operator should you use to check if two class instances have equal content?

A ===

B !==

C ==

D !=

== checks for equality of content, not identity.

Why might you want to use identity comparison in your Swift code?

A To compare two numbers

B To check if two variables point to the same object

C To sort an array

D To convert a class to a struct

Identity comparison tells you if two references point to the same object instance.

Explain the difference between === and == in Swift.

Think about what each operator compares: the object itself or its content.

When should you use identity comparison (===) in your Swift programs?

Consider situations where knowing if two things are exactly the same object matters.