To edit multiple instances of text within different sections of a document, you can use multi-cursor editing. This allows multiple cursors to be placed in different spots so text can be added, modified, or deleted.
its the name of Source Editor, for reference purpose I taken the answer from whats-new-in-xcode10 and Sample link 1 and Sample link 2
The Xcode 10 Source Editor now supports multi-cursor editing allowing you to quickly edit multiple ranges of code at once.
- shift + control + click
- shift + control + ↑
- shift + control + ↓
- option + drag
With a source control-enabled project the source editor displays changes made by a developer in the gutter and shows changes made by other developers that haven’t yet been pulled into the project