How are value types and reference types stored in memory?

Value types (struct, enum, tuple) are stored on the stack. A copy of the data is created when assigning or passing to a function.

Reference types (class, func, Closure, Array, Dictionary, Set) are stored on the heap. The stack only stores a reference to the object on the heap. When assigning or passing, only the reference is copied, not the object itself.

Example of a structure (value type):

struct Point {
    var x: Int
    var y: Int
}

var p1 = Point(x: 1, y: 2) // p1 on the stack
var p2 = p1 // p2 on the stack, a copy of p1
p2.x = 10 // Only the copy in p2 changes

Example of a class (reference type):

class Person {
    var name: String

    init(name: String) {
        self.name = name
    }
}

var person1 = Person(name: "Alice") // Person object on the heap, person1 on the stack (reference to the object)
var person2 = person1 // person2 on the stack (another reference to the same object on the heap)
person2.name = "Bob" // The property of the object referenced by person1 and person2 changes

print(person1.name) // Will output "Bob"