ios - 16 pixels margin left and right on UIView created with autolayout -

I use autolayouts for a long time and they often confuse me.

I have wired obstacles in behavior. I want to make a red scene and want to make its margin 1/1/1/1 I tap a corresponding mark in the storyboard and set the fourth barrier to 1.

left and right barriers First of all, all the values ​​are -16 and this is very strange. I do not know where Xcode takes them.

I set all the obstacles in 1 and run my application. On the screen I see the scene with the marginalized top and bottom equal to 1 and right and leave it equal to 15.

And I always have this behavior in every project. This very confuses me and does not give the UI correctly.

Does anyone know how I can escape it? Everything I need is "O, Xcode, set the margin for 1/1/1/1 for this scene" and the scene result will be 1 1/1/1 margin.

< As always, after presenting a question, I found a solution when you set up the barriers, then close the "Stop on Margin" checkbox. .