Context

Swift uses both struct and class to model data, and choosing the right one affects correctness, performance, and API design. Interviewers ask this to test understanding of value semantics, reference semantics, and object modeling.

Core Question

Explain the difference between a struct and a class in Swift. In your answer, cover:

1. How copying and assignment behave for each
2. Which features are available only to classes
3. When you would prefer one over the other in production code

Scope Guidance

Give a practical comparison rather than listing syntax only. The interviewer expects you to discuss value vs reference semantics, mutability, inheritance, memory-sharing behavior, and common use cases such as models, UI controllers, and shared mutable state. Mention trade-offs and at least one common misconception.