when in split view, is there a keyboard shortcut or gesture to toggle between the two views?

Work in Split View

In Split View, you can use both apps side by side, without the distraction of other apps.

• Choose a window to work in by clicking anywhere in that window. 
• Show the menu bar by moving the pointer to the top of the screen.
• Swap window positions by dragging a window to the other side.
• Adjust window width by dragging the vertical line between the windows.
• Switch to other apps or your desktop with Mission Control, or use a Multi-Touch gesture such as swiping left or right with four fingers on your trackpad.