UCA Unity Scripting & Programming 2 — Questions and Answers
Question 1: Which Unity method is called once per physics update, making it ideal for rigidbody force applications?
- Update()
- LateUpdate()
- FixedUpdate() (Correct answer)
- OnCollisionEnter()
Correct answer: FixedUpdate()
FixedUpdate() runs at a fixed timestep aligned with the physics engine, ensuring consistent physics calculations.
Question 2: What does the 'ref' keyword do when passed to a C# method in a Unity script?
- Creates a copy of the variable
- Passes the variable by reference allowing modification (Correct answer)
- Marks the variable as read-only
- Converts the variable to a pointer
Correct answer: Passes the variable by reference allowing modification
The 'ref' keyword passes a variable by reference, so changes inside the method affect the original variable.
Question 3: Which attribute prevents a field from appearing in the Unity Inspector while still keeping it public?
- [HideInInspector] (Correct answer)
- [NonSerialized]
- [System.NonPublic]
- [EditorOnly]
Correct answer: [HideInInspector]
[HideInInspector] hides a public serialized field from the Inspector without removing its public accessibility.
Question 4: What is the correct way to cache a component reference efficiently in Unity?
- Call GetComponent<T>() every frame in Update()
- Store the result of GetComponent<T>() in Awake() or Start() (Correct answer)
- Use FindObjectOfType<T>() each frame
- Declare the component as static
Correct answer: Store the result of GetComponent<T>() in Awake() or Start()
Caching component references in Awake() or Start() avoids the overhead of calling GetComponent<T>() every frame.
Question 5: In Unity, what does 'Instantiate()' return?
- A Transform reference only
- A GameObject reference only
- A reference to the same type as the passed object (Correct answer)
- void
Correct answer: A reference to the same type as the passed object
Instantiate() returns an Object of the same type as the argument passed, which can be cast to the appropriate type.
Question 6: Which C# keyword is used to prevent a Unity MonoBehaviour class from being inherited?
- static
- abstract
- sealed (Correct answer)
- readonly
Correct answer: sealed
The 'sealed' keyword prevents other classes from inheriting from the marked class.
Question 7: What happens if you call Destroy(gameObject) inside OnDestroy()?
- It causes infinite recursion
- It is ignored since destruction is already in progress (Correct answer)
- It destroys the object twice
- It throws a NullReferenceException
Correct answer: It is ignored since destruction is already in progress
Calling Destroy() on an object already being destroyed is safely ignored by Unity.
UCA Unity Scripting & Programming 2
Which Unity method is called once per physics update, making it ideal for rigidbody force applications?