Example link of safe area XIB.
Safe label constraints is -
Safe Area Layout Guide
is UIView
property, Safe areas help you place your views within the visible portion of the overall interface.
Safe area not covers navigation bars, tab bars, toolbars, and other ancestor views.
Use safe areas as an aid to laying out your content.
When designing for iPhone X, you must ensure that layouts fill the screen and aren't obscured by the device's rounded corners, sensor housing, or the indicator for accessing the Home screen.
Make sure backgrounds extend to the edges of the display, and that vertically scrollable layouts, like tables and collections, continue all the way to the bottom.