Display three equal-width views via AutoLayout

Demand----------"requires AutoLayout to make three views on all devices always equal width

1 "We know that fixing a control on a window requires a minimum of four constraints, so that every control needs to be constrained to

Idea---can be adjusted to the same width based on the fixed control adaptive

2 "Take lable as an example

1/Three lable on storyboard and set color to differentiate

2/Below we will constrain three lable

High

From the parent view above

From the bottom of the parent view

From the left side of the parent view

And then you have to keep them wide, before the purple view

And then the Red view.

The first one's bound to end up like this.

We were at once constrained by the other two

Set the two boundaries, adjust the spacing, and then, uh, just get three equal-width controls.

Display three equal-width views via AutoLayout