Classes are reference types in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean that classes are reference types in Swift?

It means when you assign or pass a class instance, you are working with a reference to the same object in memory, not a copy. Changes affect the original instance.

beginner

How does assigning one class instance to another variable affect the objects?

Both variables point to the same object. Changing the object through one variable changes it for the other too.

intermediate

Compare classes and structs in Swift regarding value and reference types.

Classes are reference types (shared instance), structs are value types (copied on assignment).

intermediate

What happens when you modify a property of a class instance passed to a function?

The original instance is modified because the function receives a reference to the same object.

advanced

Why is understanding reference types important when working with classes?

Because it helps avoid unexpected bugs from shared data and helps manage memory and object behavior correctly.

In Swift, what happens when you assign one class instance to another variable?

A The original object is deleted.

B Both variables refer to the same object.

C A new copy of the object is created.

D The variables become constants.

Classes are reference types, so assignment copies the reference, not the object.

Which of these is a reference type in Swift?

A Tuple

B Struct

C Enum

D Class

Only classes are reference types; structs, enums, and tuples are value types.

If you change a property of a class instance inside a function, what happens outside the function?

A The change is visible outside the function.

B The change is lost after the function ends.

C A copy is changed, original stays the same.

D The program crashes.

Functions receive a reference to the class instance, so changes affect the original.

Why might using classes lead to unexpected bugs?

A Because multiple variables can change the same object.

B Because classes cannot have properties.

C Because classes are slower than structs.

D Because classes are immutable.

Shared references mean changes in one place affect all references, which can cause bugs.

Which statement is true about structs compared to classes in Swift?

A Structs are slower than classes.

B Structs are reference types like classes.

C Structs are value types and copied on assignment.

D Structs cannot have methods.

Structs are value types, so each assignment creates a copy.

Explain in your own words what it means that classes are reference types in Swift.

Think about what happens when you assign a class instance to a new variable.

Describe the difference between how classes and structs behave when assigned to new variables.

Consider what happens if you change a property after assignment.