Quick Answer

Structs are value types with automatic memberwise initializers

Understanding the Issue

Swift structs are preferred for simple data models. They get automatic initializers, are copied on assignment, and work well with SwiftUI. Use them when you don't need inheritance or reference semantics.

The Problem

This code demonstrates the issue:

Swift Error 
// Problem: Reference semantics with class
class Point {
    var x, y: Int
    init(x: Int, y: Int) { self.x = x; self.y = y }
}
let p1 = Point(x: 1, y: 2)
let p2 = p1
p2.x = 3 // p1.x also changes

The Solution

Here's the corrected code:

Swift Fixed 
// Solution: Value semantics with struct
struct Point {
    var x, y: Int
}
let p1 = Point(x: 1, y: 2)
let p2 = p1
p2.x = 3 // p1.x unchanged

// Memberwise initializer comes free
let origin = Point(x: 0, y: 0)

Key Takeaways

Prefer structs for simple models unless you specifically need reference semantics.