Question SetActive And Get SizeDelta value

Please understand that I am not good at English before the text.

I want to get RectTransform.sizeDelta.y which is inactive object.
So I Use This Code

Code (CSharp):

1. void OnEnable()
2.     {
3.         this.transform.GetChild(1).gameObject.SetActive(true);
4.         Debug.Log(this.transform.GetChild(1).gameObject.GetComponent<RectTransform>().sizeDelta.y);
5.         this.transform.GetChild(1).gameObject.SetActive(false);
6.     }

But, It Returns 0...

How Can I fix It?

 

Well..
I used a different method.

Code (CSharp):

1. this.transform.GetChild(1).gameObject.SetActive(true);
2.         Debug.Log(this.transform.GetChild(1).gameObject.GetComponent<Text>().preferredHeight);
3.         this.transform.GetChild(1).gameObject.SetActive(false);

this code returns meaningful values

Thanks