Enable touch indicator for iOS app demo video recording
defaults write com.apple.iphonesimulator ShowSingleTouches 1






How did I find this setting?

Hidden options can be found by running the command below and then, well, figuring out what they do. They are undocumented and can be removed at any time.

strings /Applications/Xcode.app/Contents/Developer/Applications/Simulator.app/Contents/MacOS/Simulator | grep -E '^[A-Z][[:alpha:]]+$' 


If you can be bothered to go through the garbage add

| grep -E '(Enable|Disable|Show|Number)' | sort


I got 

AppleTVRemoteWindowDidShow
EnableKeyboardSync
NSDisabledCharacterPaletteMenuItem
NSDisabledDictationMenuItem
NSScreenNumber
ShowChrome
ShowChromeUIRects
ShowPinchPivotPoint
ShowPinches
ShowSingleTouches
ShowUITestMenu
TouchBarShowRemoteTemplate


ShowChrome is Window > Show Device Bezels. ShowChromeUIRects draws some lines around the bezel. The pinch ones are self descriptive. ShowUITestMenu displays a disabled menu in the simulator bar (?). I’ll test TouchBarShowRemoteTemplate when I’m back in my Macbook touch. I don’t know what the others do.

For Xcode the command should be:

strings /Applications/Xcode.app/Contents/Frameworks/IDEKit.framework/Versions/A/IDEKit | grep -E '^IDE[[:alpha:]]+$'


and the defaults command should carry the prefix com.apple.dt.Xcode. For instance 

defaults write com.apple.dt.Xcode IDEIndexerActivityShowNumericProgress 1


ShowSingleTouches is truly useful, but most options are meaningless or just noise. The command above for instance, shows you the number of files that are being indexed, instead a generic progress bar. Thus, just noise.