Collection View Preview
Here collection view is previewed based on datasource, item views and layouts set up. The view is instantly updated when any attributes or data changed. You can change the size of the Collection View Preview artboard to see how it is displayed in different screen size.
Item View Part
All item views, header and footer views and supplementary views are displayed here. Additional Item views can be added using the + button.
Layout Part
All collection view layouts are displayed here. Additional layout can be added using + button.