What is the difference between `struct` and `class` in Swift?

Answer: The core difference is value type vs reference type.

	struct	class
Type	Value type	Reference type
Memory	Stack (usually)	Heap
Inheritance	No	Yes
Mutability	Explicit (mutating)	Implicit
ARC	No	Yes
deinit	No	Yes

Rule of thumb:

• Use struct by default — safer, faster, no retain cycles
• Use class when you need identity, inheritance, or Objective-C interop