The following keyboard shortcuts are available when using an external keyboard.
Display mode
⌃⌥⌘↓ Enable split view
⌃⌥⌘↑ Disable split view
⌃⌥⌘← Show vertex shader
⌃⌥⌘→ Show framgment shader
Editor
⌘Z Undo
⌘⇧Z Redo
⌘X Cut
⌘C Copy
⌘V Paste
⌘/ Un-/comment selection
Code completion
⇥ Longest prefix
Code completion is independent of the use of an external keyboard. The selected completion result can be changed by tapping another item in the list. The tab-key inserts the longest prefix and tapping the selected item or the return-key inserts the selected item.