Unexpected result for autolayout on iphone 6 plus

I've added a uiview on a view controller(VC), trying to set it's width is equals to VC's view's width.

What I set and expected:

And what i got on iphone 6 plus:

I've tried to change the constants of leading space and trailing space and no help. Is there any special for iphone 6+ autolayout?

The view setting here is "Any width x Regular height"

-------Added Dec 2016 To people who is confused by this case like me: There is a layout margin property in UIView, which is an UIEdgeInsets(8,8,8,8). It is something like css padding.

When the edge of your view is close to the edge of the superview and the preservesSuperviewLayoutMargins property is true, the actual layout margins may be increased to prevent content from overlapping the superview’s margins.

The default margins are eight points on each side.

If the view is a view controller’s root view, the system sets and manages the margins. The top and bottom margins are set to zero points. The side margins vary depending on the current size class, but can be either 16 or 20 points. You cannot change these margins.

Try to remove the check Constrain to margins when adding constraints. Here take a look:

Constrain to margins is checked and its result

Now, after removing the constraints and re-adding the constraints with Constrain to margins unchecked, here is the result: