I can't create RectTransform in Awake when the GameObject is inactive at first.

I am using Unity 5.5.2p2, and I am create a RectTransform in the Awake like this:

Code (CSharp):

1.  
2. void Awake()
3. {
4.     var go = new GameObject("New", typeof(RectTransform));
5.     go.transform.SetParent(this.transform);
6. }
7.  

And if the gameobject is inactive, and I active it by other logic or manual active it in inspector when unity is playing, it appear the error:

This change break most of my logic, and it seems introduce recently. In 5.5.1 I never met this problem.

 

I find someone met the same problem.
http://digitalnativestudios.com/forum/index.php?topic=1479.msg10999#msg10999

They avoid new GameObject but use Instantiate to avoid this bug, but I think it should be fixed.

 

Have you tried the templated (generic) form:

Code (csharp):

1.          var rt = new GameObject ("New").AddComponent<RectTransform> ();

 

No，I test it but the result is still the same:

I test the newst version 5.5.2p3, the problem is still the same. But the 5.5.2p1 is fine.

 

We have this issue with 5.5.3 too

 

From the documentation on GameObject constructors

https://docs.unity3d.com/ScriptReference/GameObject-ctor.html

Since a RectTransform is a Transform and a GameObject can only have a single Transform on it attempting to add one via code fails (as you've seen). Since the constructors have been around way longer than RectTransform and the new UI system I would imagine that this is an overlooked feature. I'd suggest creating a feature request to be able to create GameObjects with RectTransform components via code

 

For your information, I found this in doc, we must create a UIElements by a prefab
https://docs.unity3d.com/Manual/HOWTO-UICreateFromScripting.html

 

If you check here:

http://answers.unity3d.com/questions/948887/what-is-the-correct-syntax-to-create-a-new-object.html

You can see it is possible with just this codelet:

Code (csharp):

1. GameObject myGO = new GameObject("MyGO", typeof(RectTransform));

I just tried it, it works as expected: I now have a new GameObject with a RectTransform instead of a Transform.

That said, it is probably better to play in the Prefab context, because then when you hire an artist or designer who doesn't know how to write code, they can use the Unity engine to change your prefab and you don't have to touch your code.

 

Take a look at the first post, this raise an error with some unity versions. BTW documentation is often more reliable than forums.