The margins used to lay out content in a section
- iOS 6.0+
- tvOS 9.0+
If the delegate object does not implement the
collection method, the flow layout uses the value in this property to set the margins for each section.
Section insets reflect the spacing at the outer edges of the section. The margins affect the initial position of the header view, the minimum space on either side of each line of items, and the distance from the last line to the footer view. The margin insets do not affect the size of the header and footer views in the non scrolling direction.
The default edge insets are all set to 0.