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Architecture UI In Unity: MVC, MVP & MVVM

Minh Khoa

Minh Khoa

Author

UI Architecture in Unity: MVC, MVP, MVVM

**Goal:**Understand clearly why UI and logic are often a "mess" in Unity, master three professional architectures (MVC, MVP, MVVM) and know how to apply them appropriately to each real-world situation.

image.png

πŸ“Œ INTRODUCTION β€” IDENTIFYING THE REAL PROBLEM

Example Anti-Pattern

// NewStationUI.cs β€” UI class
private void RefreshUI()
{
    bool canAfford = GameController.Instance != null
                     && GameController.Instance.CanAfford(cost);

    unlockButton.interactable = canAfford;
}

private void OnClickUnlock()
{
    if (GameController.Instance.SpendMoney(_currentData.UnlockCost))
    {
        _currentData?.OnConfirm?.Invoke();
        Hide();
    }
}

// GamePlayScreen.cs β€” UI class
public void UpdateUpgradeIconState()
{
    var upgrades = DatabaseManager.Instance?.InitConfig?.Upgrades;

    if (upgrades != null && GameController.Instance != null)
    {
        foreach (var data in upgrades)
        {
            if (!UpgradeState.IsPurchased(data.ID)
                && GameController.Instance.CanAfford(data.Price))
            {
                canAffordAny = true;
                break;
            }
        }
    }
}

Problem

  • UI know too much about the system.
  • Logic is scattered.
  • Hard to test.
  • Hard to maintain.
  • Designer edits UI can break the logic.

πŸ”‘ PART 1 β€” SEPARATION OF CONCERNS

Model

  • Manages data.
  • Contains business logic.
  • Does not know UI exists.

View

  • Only displays.
  • Receives input from the user.
  • Does not contain business logic.

Controller / Presenter / ViewModel

  • Connects Model and View.
  • Coordinates the data flow.
  • Does not contain UI detailed code.

πŸ”· PART 2 β€” MVC

Data Flow

User Input
    ↓
   View
    ↓
Controller
    ↓
  Model
    ↓
 Notify
    ↓
   View

Advantages

  • Simple.
  • Little boilerplate.
  • Easy to learn.

Disadvantages

  • Coupling between View and Model.
  • Controller easily bloats.
  • Harder to test MVP.

πŸ”Ά PART 3 β€” MVP

Data Flow

User Input
    ↓
   View
    ↓
Presenter
    ↓
  Model

Presenter
    ↓
   View

Characteristics

  • View does not know the Model.
  • Presenter is the only bridge.
  • Uses Interface for communication.

Advantages

  • Easy to test.
  • View is extremely "dumb."
  • Easy to maintain.

Disadvantages

  • Many Interfaces.
  • Presenter easily bloats.

🟣 PART 4 β€” MVVM

Data Flow

Model
  ↕
ViewModel
  ↕
Data Binding
  ↕
 View

Characteristics

  • Uses ReactiveProperty / Observable.
  • View updates itself.
  • No need to call RefreshUI manually.

Advantages

  • Reactive.
  • Strong Data Binding.
  • Good testability.

Disadvantages

  • High learning curve.
  • Adds dependency (UniRx / R3).
  • Easy over-engineering.

πŸ—οΈ PART 5 β€” PRACTICAL APPLICATION

Screens

Recommendation:

  • Thin Presenter
  • EventBus
  • Screen only renders

Popups

Recommendation:

  • MVP

Example:

  • NewStationPopup
  • UpgradePopup
  • ConfirmationDialog

Widgets

Recommendation:

  • MVVM-lite
  • ReactiveProperty Binding

For example:

  • MoneyBar
  • HealthBar
  • Minimap

🚨 PART 6 β€” ANTI-PATTERNS

1. Circular Reference

UI β†’ Controller
↑       ↓
β””β”€β”€β”€β”€β”€β”€β”€β”˜

Signs

  • UI directly calls Singleton.
  • Singleton holds a reference UI.

2. Fat View

private void OnEnable()
{
    var model = StationManager.Instance.GetCurrentStation();

    titleText.text = model.Name;
}

The View is doing the Presenter’s work.

3. Anemic Presenter

public void OnUnlock()
{
    _model.Unlock();
}

The Presenter only forwards.

4. Over-Engineered ViewModel

public ReactiveProperty<float> ButtonWidth;
public ReactiveProperty<Color> ButtonColor;
public ReactiveProperty<Vector2> ButtonPosition;

Not everything needs ReactiveProperty.

βš–οΈ PART 7 β€” WHEN TO USE WHICH?

MVC

Use when:

  • Small game.
  • Small team.
  • Need to ship quickly.

MVP

Use when:

  • UI complex.
  • Need Unit Tests.
  • Designer and Programmer work independently.

MVVM

Use when:

  • MMO.
  • Dashboard.
  • Realtime data.
  • Reactive workflow.

🎯 CONCLUSION

3 golden questions

  1. Remove UI does the Logic still run?
  2. Change UI does the Layout need Logic changes?
  3. Does Logic testing need Unity?

If all 3 answers areYes→ the architecture is heading in the right direction.

Good architecture is not about using patterns β€” it's about being able to change your mind later without rewriting everything.