Try:
- Go to Xcode > Preferences > Text Editing
- Under Code completion – Uncheck ‘Suggest completions while typing’
- Quit out of Xcode and then relaunch Xcode.
- Go to Xcode > Preferences > Text Editing again
- Quit out of Xcode and then relaunch Xcode.
- Now go to Code completion and check ‘Suggest completions while typing’.
- Try typing library function or enum and enjoy!