`struct` vs `class` vs `actor` - Comparison

	Structs	Classes	Actors
Type	Value type	Reference type	Reference type
Inheritance	❌	✅	❌
Thread−safety	✅	❌	✅
Memberwise Initializer	✅	❌	❌
Deinitializer	❌	✅	✅
Memory allocation	Stack	Heap	Heap
External access to public properties and methods	direct		direct, but by using `await`
Protocols		conform to the `AnyObject` can therefore conform to `Identifiable` without adding an explicit id property	conform to the `AnyObject` can therefore conform to `Identifiable` without adding an explicit id property conform to the `Actor`
Method execution	Can potentially be executing severals methods at a time		Can execute only one method at a time
Other	Can: have initializers have properties have methods have subscripts have extensions conform to protocols

Structs

It's a value type (along with e.g. arrays, dictionaries, enums and tuples).
- Every time you use the struct reference in your code, it is potentially a new struct.
  - But Swift copy that new struct to a new memory address only if you modify the struct.
  - It called copy-on-write pattern. It's a memory optimization.
Structs cannot cause memory leaks.

Apple recommendation: use structures by default for storing data and modeling behavior.
When you don't need class' features:
- You don't need to control the object's identity (use the identity operator ===).
- You don't need a shared mutable state feature.
- You don't need Objective-C interoperability.
- You don't need class inheritance.
- You need to replace class inheritance:
  - Protocols and structures can replace class inheritance.

You need to control the object's identity (use the identity operator ===).
You need a shared mutable state feature.
You need Objective-C interoperability.
You need class inheritance.

You need to use a reference type.
You need thread safety for shared mutable state.
- It eliminates all kinds of race conditions and data races.