Unity C# Fundamentals - Essential Coding Patterns

Overview

Core Unity C# patterns for safe, maintainable code. Not optimizations but fundamental practices.

Foundation Required: C# basics, Unity MonoBehaviour lifecycle

Core Topics: TryGetComponent, SerializeField, RequireComponent, Null-safe patterns, Lifecycle management

Essential Patterns

TryGetComponent (Required)

Always use TryGetComponent instead of GetComponent :

// ❌ WRONG Rigidbody rb = GetComponent<Rigidbody>(); rb.velocity = Vector3.zero; // NullReferenceException!

// ✅ CORRECT Rigidbody rb; if (TryGetComponent(out rb)) { rb.velocity = Vector3.zero; }

// ✅ Cache in Awake with validation private Rigidbody mRb;

void Awake() { if (!TryGetComponent(out mRb)) { Debug.LogError($"Missing Rigidbody on {gameObject.name}", this); } }

Global Object Search (Unity 2023.1+)

// ❌ OBSOLETE - DON'T USE GameManager manager = FindObjectOfType<GameManager>();

// ✅ CORRECT - Fastest (unordered) GameManager manager = FindAnyObjectByType<GameManager>();

// ✅ CORRECT - Ordered GameManager manager = FindFirstObjectByType<GameManager>();

// ✅ Multiple objects Enemy[] enemies = FindObjectsByType<Enemy>(FindObjectsSortMode.None);

SerializeField Pattern

// ❌ WRONG: Public field public float speed;

// ✅ CORRECT: SerializeField + private [SerializeField] private float mSpeed = 5f;

// ✅ With Inspector helpers [SerializeField, Tooltip("Units/second"), Range(0f, 100f)] private float mMoveSpeed = 5f;

public float Speed => mSpeed; // Read-only access

RequireComponent

[RequireComponent(typeof(Rigidbody))] [DisallowMultipleComponent] public class PhysicsObject : MonoBehaviour { private Rigidbody mRb;

void Awake()
{
    TryGetComponent(out mRb);  // Guaranteed to exist
}

}

Unity Null Safety

// ❌ WRONG: C# null operators don't work with Unity Objects Transform target = mCached ?? FindTarget(); // Broken! mEnemy?.TakeDamage(10); // May fail after Destroy

// ✅ CORRECT: Explicit null check Transform target = mCached != null ? mCached : FindTarget();

if (mEnemy != null) { mEnemy.TakeDamage(10); }

Lifecycle Order

void Awake() { /* 1. Self-init, cache components / } void OnEnable() { / 2. Subscribe events / } void Start() { / 3. Cross-object init / } void OnDisable() { / 4. Unsubscribe events / } void OnDestroy() { / 5. Final cleanup */ }

Unity C# 9.0 Limitations

Important: Unity's Mono/IL2CPP runtime lacks IsExternalInit . init accessor causes compile error CS0518.

// ❌ COMPILE ERROR in Unity public string Name { get; private init; }

// ✅ Use private set public string Name { get; private set; }

// ✅ Or readonly field + property private readonly string mName; public string Name => mName;

Available: Pattern matching, switch expressions, covariant returns NOT Available: init , required (C# 11)

Quick Reference

Pattern Rule

Component access Always TryGetComponent , never bare GetComponent

Serialization [SerializeField] private , not public

Dependencies Use [RequireComponent] for guaranteed components

Null checks Explicit != null , not ?? or ?.

Caching Get in Awake , reuse everywhere

Events Subscribe in OnEnable , unsubscribe in OnDisable

Global search FindAnyObjectByType (fastest), not FindObjectOfType

Reference Documentation

Component Access Patterns

• TryGetComponent variations and interface-based access

• GetComponentInChildren/Parent patterns

• Allocation-free multiple component access

• Caching strategies and performance comparisons

Attributes and Patterns

• Complete serialization attribute reference

• Inspector customization (Header, Tooltip, Range)

• Execution order control

• Conditional compilation

Language Limitations

• init accessor alternatives with code examples

• Records in Unity (limitations and workarounds)

• required modifier alternatives

• Available C# 9.0 features in Unity