It is possible with Xcode 10+, see the wwdc2018 presentation of the functionality.
Ways to create multiple cursors:
- ⇧ Shift + ⌃ Control + Left Mouse Click: Will create a new cursor on every click
- ⇧ Shift + ⌃ Control + ↑: Will create a new cursor above
- ⇧ Shift + ⌃ Control + ↓: Will create a new cursor bellow
- ⌥ Option + drag: Will create a new cursor on every line you drag
preview:

For more information, see this answer