Why Views Need State
Understand why SwiftUI views are immutable.
Why Views Need State is a free SwiftUI Academy lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the SwiftUI Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Views Describe, They Don't Hold
A SwiftUI view is a lightweight description of your UI for one moment. It is recreated constantly, so it can't simply store changing values like a normal object. 📐
Structs Are Immutable
Your views are structs, and SwiftUI treats their stored properties as read-only inside body. You cannot just reassign a property and expect the screen to react.
struct CounterView: View {
var count = 0
var body: some View {
Text("Count: \(count)")
}
}Why Reassigning Fails
Try setting a plain property from a button and the compiler stops you: structs can't mutate themselves inside body. The UI has no idea anything changed anyway.
The UI Is a Function of Data
In SwiftUI, the screen is a pure function of your data. Same data in, same UI out. To change the screen, you change the data, not the view directly.
Enter State
SwiftUI gives you state: a place to store changing values that lives outside the throwaway view struct. When state changes, SwiftUI rebuilds the affected views for you. ✨
State Survives Redraws
Even though the view struct is recreated again and again, your state value persists between redraws. SwiftUI stores it safely behind the scenes for that view.
The Source of Truth
State becomes the single source of truth for a piece of view-local data. The view always reflects it, so there is never a stale, out-of-sync screen.
A Tiny Example
Here a stored value drives the text. Once it is marked as state, changing it will automatically refresh the Text on screen.
struct GreetingView: View {
@State private var name = "Sam"
var body: some View {
Text("Hi, \(name)")
}
}Reactive, Not Imperative
You never tell a label to update itself. You change the data and SwiftUI reacts. This declarative style means less wiring and fewer bugs.
When You Need State
Use state for values a single view owns and changes over time: a counter, a toggle, typed text. Static labels and fixed config don't need it.
Keep State Small
State is meant for simple, view-local data. Keep each piece focused so SwiftUI can update efficiently and your views stay easy to reason about.
Quick Check
Why can't a SwiftUI view just store a changing value in a plain property?
Recap
SwiftUI views are immutable structs and the UI is a function of data. State lets a view own changing values that persist across redraws and drive automatic updates. 🎯
Frequently asked questions
Is the “Why Views Need State” lesson free?
Yes — the full text of “Why Views Need State” is free to read here on the web, and the SwiftUI Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the SwiftUI Academy course, upgrade to CoddyKit PRO.
What will I learn in “Why Views Need State”?
Understand why SwiftUI views are immutable. You practise SwiftUI Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start SwiftUI Academy?
No prior experience is required. SwiftUI Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Why Views Need State” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this SwiftUI Academy lesson?
Yes. Every SwiftUI Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Why Views Need State
- Declaring @State Properties
- Building a Tap Counter
- Toggling Visibility with State