My current project uses some symbols which are absent in many fonts. So far I've found some iOS renders as a box so I'm expecting sooner or later to find one that Android can't render too, though so far it's done better than iOS in this regard.
Is there a way to programatically check that a given Unicode codepoint will display correctly on the screen and not as an empty square box etc?
If I can detect a symbol can't be rendered I can implement a workaround for it rather than display an ugly box.