Get the size of a rectTransform with ContentSizeFilter Attached

I am currently messing up with some customized text view stuff. As the above picture indicates, i added a content size filter to the text, so that it would resize with it's content, this works fine.
But now in my code, i want to access its derived height, i.e the grayed number 30.6...
normally with a RectTransform , i just need to use .rect.height to get its height, but as in
this case, it always return 0. Does anyone know how to get the height in this case

 

As far as I was aware .rect.height should give the proper height, maybe you have to wait a frame for it to be set or something depending on when/where you're looking at .rect.height.

 

Thanks DWilliams
Indeed, I have to wait for the end of the frame in order to get the height