Autolayout: keep view's centerX same with another View but not overstep its superView

Question

There are two subviews in yellow view: red view and green view. Both of them have fixed width and height. greenView has two more constraint: leading and bottom to the yellow View. redView has two more constraint: vertical space between bottom to the greenView's top and same centerX with greenView. (Figure 1) (Figure 1)

What I need to do is, always keep redView inside of the yellow View, even if green view's leading constraint to the yellow view is Zero.(Figure 2) What should I do with AutoLayout? Any idea? Thanks. (Figure 2)

Answer 1

This example makes 3 constraints to the orange view:

1. Leading space >= 0 (priority 1000)
2. Trailing Space >= 0 (priority 1000)
3. CenterX to the green box (priority 999)

Result: (I forgot to remove the margin)