Structs vs classes in iOS Swift - Quick Revision & Key Differences

Recall & Review

beginner

What is a struct in Swift?

A struct is a value type that stores data and copies itself when assigned or passed around. It is often used for simple data containers.

beginner

What is a class in Swift?

A class is a reference type that stores data and shares the same instance when assigned or passed around. It supports inheritance and reference counting.

intermediate

How do structs and classes differ in memory behavior?

Structs copy their data when assigned or passed, so each variable has its own copy. Classes share the same instance, so changes affect all references.

intermediate

Can structs inherit from other structs or classes?

No, structs cannot inherit from other structs or classes. Only classes support inheritance in Swift.

beginner

When should you choose a struct over a class in Swift?

Choose a struct when you want simple, safe data containers that copy on assignment and don’t need inheritance or shared state.

Which of the following is true about Swift structs?

A They are reference types.

B They support inheritance.

C They are value types and copy on assignment.

D They cannot have methods.

Structs are value types and copy their data when assigned or passed. They do not support inheritance but can have methods.

What happens when you assign a class instance to a new variable?

A A new copy of the instance is created.

B The new variable points to the same instance.

C The instance is deleted.

D The instance becomes immutable.

Classes are reference types, so assigning them copies the reference, not the data. Both variables point to the same instance.

Which feature is only available in classes but not structs?

A Inheritance

B Stored properties

C Methods

D Initializers

Only classes support inheritance in Swift. Structs cannot inherit from other types.

Why might you prefer structs for simple data models?

A Because they are reference types.

B Because they automatically share data.

C Because they support inheritance.

D Because they copy data, avoiding unexpected changes.

Structs copy their data on assignment, so each variable has its own copy, which helps avoid bugs from shared state.

Which of these is NOT a characteristic of Swift classes?

A Copies data on assignment

B Supports inheritance

C Reference type

D Can have deinitializers

Classes do not copy data on assignment; they share references. Structs copy data on assignment.

Explain the main differences between structs and classes in Swift.

Think about how data is stored and shared.

When would you choose a struct instead of a class for your data model in an iOS app?

Consider safety and simplicity.