问题
how to give constraints for the buttons in the bottom as shown in image.
回答1:
select all 5 UIButtons and give equal widths constraints. give following constraints forr all buttons:
1.Height constraint.
2.Leading Constraint.
2.Bottom Constrain.
4.Equal Width Constraint
5.Trailing Constraint(if necessary)
check here :Arrange 3 UIButtons(of equal width) side-by-side
来源：https://stackoverflow.com/questions/36515549/how-to-give-constraints-for-uibuttons