[Stroke rectangle equivalent in Affinity Photo (iPad)?]

I know I'm late to this thread, but I was struggling with the same thing this morning, and the answers here didn't help much.  Hopefully this will help someone else.  To create a simple transparent rectangle in Affinity Photo, do these 2 steps:

1. Create a rectangle using the "Rectangle Tool".
   
2. With the rectangle drawn & selected, click "Fill" and then click the circle with the red line through it.
   

You'll end up with this:

 

Hopefully this helps,

Toby