What’s the difference between a class and a struct?
Swift version: 5.6
Classes and structures (structs) are so similar in Swift that it's easy to get them confused at first, but actually there are some important underlying differences:
- A struct cannot inherit from another kind of struct, whereas classes can build on other classes.
- You can change the type of an object at runtime using typecasting. Structs cannot have inheritance, so have only one type.
- If you point two variables at the same struct, they have their own independent copy of the data. With objects, they both point at the same variable.
That last point is particularly important: with a struct you know your data is fixed in place, like an integer or other value. This means if you pass your struct into a function, you know it's not going to get modified.
SPONSORED Join a FREE crash course for mid/senior iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a complete senior developer! Hurry up because it'll be available only until April 28th.
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 7.0
Similar solutions…
- What is a nested class or nested struct?
- What’s the difference between a static variable and a class variable?
- What’s the difference between a protocol and a class?
- How to automatically switch between HStack and VStack based on size class
- What’s the difference between async let, tasks, and task groups?
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
