The minimum spacing to use between lines of items in the grid.
- 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 spacing between lines in a section.
For a vertically scrolling grid, this value represents the minimum spacing between successive rows. For a horizontally scrolling grid, this value represents the minimum spacing between successive columns. This spacing is not applied to the space between the header and the first line or between the last line and the footer.
The default value of this property is 10.0.