如何解决不存在的错误转换？

Question

using UnityEngine;
using System.Collections;

public class MakeTwoPoints3D : MonoBehaviour {

    public GameObject cylinderPrefab;

    // Use this for initialization
    void Start () {

        CreateCylinderBetweenPoints(Vector3.zero, new Vector3(10, 10, 10), 0.5f);

    }

    void CreateCylinderBetweenPoints(Vector3 start, Vector3 end, float width)
    {
        var offset = end - start;
        var scale = new Vector3(width, offset.magnitude / 2.0f, width);
        var position = start + (offset / 2.0f);


        Object cylinder = Instantiate(cylinderPrefab, position, Quaternion.identity);
        cylinder.transform.up = offset;
        cylinder.transform.localScale = scale;
    }

    // Update is called once per frame
    void Update () {

    }
}

On both lines same error:

cylinder.transform.up = offset;
cylinder.transform.localScale = scale;

Severity Code Description Project File Line Suppression State Error CS1061 'Object' does not contain a definition for 'transform' and no extension method 'transform' accepting a first argument of type 'Object' could be found (are you missing a using directive or an assembly reference?) MakeTwoPoints3D.cs 23 Active

Answer 1

Object is parent class of GameObject and GameObject as member of type Transform . If you try to access transform from an instance of Object class, it will show you following error:

Object' does not contain a definition for 'transform'

So accurate way of instantiating and using the resulted object as a GameObject is as Quantic said in comment :

GameObject cylinder = Instantiate(cylinderPrefab, position, Quaternion.identity) as GameObject;

OR

GameObject cylinder = (GameObject) Instantiate(cylinderPrefab, position, Quaternion.identity);

It is always to use null-check for safety before using the component in case of other types than GameObject. For example:

Rigidbody rb = Instantiate(somePrefab) as Rigidbody;
if(rb != null)
  // use it here

hope this helps.