When Full Keyboard access is enabled, the currently focused element is indicated by a thick border (first screenshot below). If the focused element is inside a focus group, e.g. a UIScrollView, then the thick border encloses the entire focus group, and the focused element is indicated by a change in background color instead (second screenshot below). These two types of focus state seem to use the tintColor of the element.
We were advised that the change in background color does not meet WCAG standards since the contrast ratio between the non-focused state and the light blue focused state is not high enough.
Apart from changing the tintColor, is there any other way to customize the focused appearance of an element? It would be ideal if we could apply a border to the focused element even when it's contained in a focus group, rather than just changing the background color.