Swift中Struct和Class的区别

Struct	Class
Value type	Reference type
Copied when passed or assigned	Passed around via pointers
Copy on write	Automatically reference counted
Functional programming	Object-oriented programming
No inheritance	Inheritance (single)
“Free” init initializes ALL vars	“Free” init initializes NO vars
Mutability is explicit (var vs let)	Always mutable
Your “go to” data structure	Used in specific circumstances
Everything you’ve seen so far is a struct (except View which is a protocol)	The ViewModel in MVVM is always a class (also, UIKit (old style iOS) is class-based)