Note: This is related to my recent adventures in Dark Mode for iOS.
I was using the quasi-standard hamburger to indicate a menu. The problem was that I was using an image. So, when the phone was in Dark Mode, it basically disappeared. Was there an emoji hamburger? There are a bunch (not including all the images of actual edible hamburgers).
The unicode for the one I used is: &u2630. This worked fine; change to Dark Mode and all the lines turn white.
I had make a control (now a button and a label) so I only needed to make a change in one place to get this to work. One does have to change the font size of the label to get it big enough.