The main problem is that when they're black, there's no "darker" color of black. So all the segments are the same color.
What you can do is imagine how it would look. Then go and make your segmented control dark gray 😛.
To the OP, there's no way to tint them in IB which is really weird. You'd have to do it programatically through the tintColor property.
Set it to a dark gray color and then it should work fine.