class와 struct의 차이를 메모리구조와 관련해서 설명해줘

In Swift, the primary difference between classes and structs in terms of memory structure is how they store their data and manage memory:

1. Structs:

   • Inline Storage: Structs use inline storage, meaning all of their stored properties are laid out directly in the memory space allocated for the struct itself. This can lead to more efficient memory usage for small data types because it avoids heap allocation.
   • Value Semantics: When you copy a struct, you are copying all of its data. This means each copy is independent, which can be beneficial for ensuring data integrity but may lead to higher memory usage if the struct is large and copied frequently.

2. Classes:

   • Out of Line Storage: Classes use out of line storage, which means they store their data in a separate memory location (the heap), and the class instance itself holds a reference (pointer) to this data.
   • Reference Semantics: Copying a class instance means copying the reference to the data, not the data itself. This allows multiple references to the same data, which can be more memory efficient but requires careful management to avoid unintended side effects from shared state.

The choice between using a struct or a class can have significant performance implications, especially in terms of memory allocation and copying behavior. For example, copying a large struct can be costly because it involves duplicating all of its data, whereas copying a class instance is cheaper since it only involves copying a reference.

For more detailed information, you can refer to the session Explore Swift performance (13:57) which discusses value copying and memory layout in Swift.