Xcode auto layout constraints - why defaulting to negative padding?

Question

I am simply adding a UIView into the main view of a view controller. I want the height to always be 64px, but the width to stretch to the width of the screen.

However, when I go to add constraints, the left and right padding default to -16, even though the view is stretched all the way across its parent view. Even if I set these back to 0, when I run the app the -16 padding is added back in. What is going on here?

Answer 1

取消选中pin菜单中的“Constrain to margins”复选框 （问题中的第一个图像），同时为新约束添加间隔到最近邻居 。