How to create and instantiate game object from C# script

I am creating a game object using C# script in the following way:

Code (CSharp):

1.  using UnityEngine;
2.   using System.Collections;
3.  
4.   public class TestingPositions : MonoBehaviour {
5.  
6.   GameObject hero;
7.   Sprite heroSprite;
8.   Vector3 heroPosition;
9.   // Use this for initialization
10.   void Start () {
11.   Instantiate (hero, heroPosition, Quaternion.identity);
12.   Camera camera = GetComponent<Camera>();
13.   heroPosition = camera.ScreenToWorldPoint(new Vector3(Screen.width/2, Screen.height/2, camera.nearClipPlane));
14.   heroSprite = Resources.Load <Sprite> ("Sprites/heroImage");
15.   SpriteRenderer renderer = hero.AddComponent<SpriteRenderer>();
16.   renderer.sprite = heroSprite;
17.   }

I am getting the following error when I run the app:

Code (CSharp):

1.   ArgumentException:The thing you want to instantiate is null.  `UnityEngine.Object.CheckNullArgument(System.Object, System.string message)

pointing to the line:

Code (CSharp):

1.   Instantiate (hero, heroPosition, Quaternion.identity);

How can I solve this issue?

 

Instantiate is used to make a new instance (clone) of an existing game object or prefab. If you want to make a brand new game object, you can do this to make a game object with a sprite renderer component:

Code (CSharp):

1. GameObject hero = new GameObject("Hero", typeof(SpriteRenderer));

 

Basically, I added my C# script to an empty game object in the inspector. I believe I am suppose to replace the Instantiate with the line of code you stated above, which is what I've done, but now I am getting the following error:

MissingComponentException: There is no 'Camera' attached to the "Hero" game object, but a script is trying to access it.
You probably need to add a Camera to the game object "Hero". Or your script needs to check if the component is attached before using it.
TestingPositions.Start () (at Assets/Scripts/TestingPositions.cs:42)

I already have the default Main Camera in the inspector

 

I've solved it, I accessed the main camera through it's tag

 

You can use "Camera.main" to reference the current camera in the scene with the MainCamera tag.