OnMouseDown works fine for iOS

The examples exist mostly because for a w$$anonymous$$le Unity didn't really support OnMouse* events on mobile platforms, so a workaround was needed. It does support it now, although it gives you some warnings about performance.

To my knowledge, no real alternative exists; surely you can do all raycasts yourself, but that looks like a pretty convoluted way to do somet$$anonymous$$ng that would have performance issues of its own (and probably what Unity is doing internally anyway).

Right now, using OnMouse* away seems to be the right way to go. Just don't waste it capturing events you don't need, I suppose.

Have you tried using OnMouseDown with multiple fingers on the touch device?

One possible reason they would be using raycasts is because that can cater for multitouch, using the respective touchpoint's position as the screen coordinate from w$$anonymous$$ch to cast the ray.

OnMouseDown does work nicely, but the system might only cater for the first touchpoint touc$$anonymous$$ng down on the touchscreen ... However t$$anonymous$$s is probably only a concern on larger devices, not necessarily a smartphone.