Comparing structs vs classes decision in Swift - When to Use Which

The Big Idea

What if choosing the wrong data type silently breaks your app's logic?

The Scenario

Imagine you are building a contact list app. You try to keep track of each contact's details by copying and updating information everywhere manually.

You write separate code to copy data, update it, and make sure changes reflect correctly in all places.

The Problem

This manual copying and updating is slow and confusing. You might forget to update some copies, causing wrong or outdated info.

It's hard to know when to share data or keep separate copies, leading to bugs and frustration.

The Solution

Using structs and classes helps you decide how data should behave: structs make copies automatically, classes share one copy.

This choice makes your code clearer, safer, and easier to manage without extra manual work.

Before vs After

✗ Before

class Contact {
    var name: String
    init(name: String) {
        self.name = name
    }
}

var contact1 = Contact(name: "Alice")
var contact2 = contact1
contact2.name = "Bob"  // manual copy and update

✓ After

struct Contact { var name: String }
var contact1 = Contact(name: "Alice")
var contact2 = contact1
contact2.name = "Bob"  // struct copies automatically

What It Enables

It enables you to write clean, bug-free code by choosing the right data behavior for your app's needs.

Real Life Example

In a drawing app, you want shapes to be independent copies (structs) so changing one doesn't affect others, but for a shared settings manager, you want one shared instance (class) to keep settings consistent.

Key Takeaways

Manual copying of data is error-prone and confusing.

Structs automatically copy data; classes share one instance.

Choosing between them makes your code safer and easier to understand.