convert transform position in canvas to screen space coordinates

Hello!

Since i never found the correct answers I am looking for in the forum, i have
to ask here. I simply need a function, where I can convert a transform position in a
canvas object to the position in my screen space.
I found one answer here http://answers.unity3d.com/questions/826851/how-to-get-screen-position-of-a-recttransform-when.html.

But this function is not longer provided in the newer versions…
So please can someone tell me what to do? I dont understand the new " RectTransformUtility"
functions…

If you have Render Mode: Screen space - Overlay in your canvas and you want to know what are the corner positions of RectTransform in Screen space coordinates then RectTransform.GetWorldCorners should work.

Vector3[] worldCorners = new Vector3[4];
myRectTransformObject.GetWorldCorners(worldCorners);
var bottomLeft = worldCorners[0];
var topLeft = worldCorners[1];
var topRight = worldCorners[2];
var bottomRight = worldCorners[3];