unity-development

Unity Development Guide

A comprehensive guide for Unity development. This skill serves as always-referenced parent skill, providing common patterns and tool selection guidance.

Architecture Patterns

Fail-Fast Principle

Do not write null checks. Use objects directly when their existence is assumed.

// NG: Forbidden pattern
if (component != null) { component.DoSomething(); }
if (gameObject != null) { gameObject.SetActive(false); }
if (service != null) { service.Execute(); }

// OK: Correct pattern - direct usage
GetComponent<Rigidbody>().velocity = Vector3.zero;
GameService.Initialize();
target.position = Vector3.zero;

Applies to:

• Null check after GetComponent<T>()
• Null check after Find*()
• Null check after [Inject]

No GetComponent in Update

GetComponent every frame causes GC allocation and performance degradation. Cache in Awake.

// NG: GC allocation every frame
void Update()
{
    GetComponent<Rigidbody>().velocity = input;
}

// OK: Cache in Awake
private Rigidbody _rb;

void Awake()
{
    _rb = GetComponent<Rigidbody>();
}

void Update()
{
    _rb.velocity = input;
}

UniTask Patterns

Use UniTask instead of coroutines. async void is forbidden.

using Cysharp.Threading.Tasks;

// NG: async void
async void Start()
{
    await DoWorkAsync();
}

// OK: UniTaskVoid + destroyCancellationToken
async UniTaskVoid Start()
{
    await DoWorkAsync(destroyCancellationToken);
}

// OK: When return value is needed
async UniTask<int> CalculateAsync(CancellationToken ct)
{
    await UniTask.Delay(1000, cancellationToken: ct);
    return 42;
}

Best Practices:

• Use destroyCancellationToken for auto-cancel on GameObject destruction
• UniTask.Delay > Task.Delay (zero allocation)
• UniTask.WhenAll for parallel execution

VContainer DI

Use VContainer for dependency injection. Constructor injection recommended.

// Interface definition
public interface IPlayerService
{
    void Initialize();
}

// Implementation class
public class PlayerService : IPlayerService
{
    public void Initialize() { /* ... */ }
}

// Consumer (MonoBehaviour)
public class GameManager : MonoBehaviour
{
    [Inject] private readonly IPlayerService _playerService;

    void Start()
    {
        _playerService.Initialize();
    }
}

// LifetimeScope configuration
public class GameLifetimeScope : LifetimeScope
{
    protected override void Configure(IContainerBuilder builder)
    {
        builder.Register<IPlayerService, PlayerService>(Lifetime.Singleton);
        builder.RegisterComponentInHierarchy<GameManager>();
    }
}