Deleting plist file does not reset app on macOS 10.9+

Question

While developing a Cocoa application on 10.9, I have noticed that if I go to ~/Library/Preferences and delete the plist file for my app (to reset it), on the next build-and-run, the app behaves as if the plist file had never been deleted at all.

It took me a long time to track down why this happens and I did not see a question/answer about it on SO, so I'm writing this question and answering it myself to help others.

Answer 1

On 10.9, the system is doing some more robust "caching" of preferences. After deleting the plist file, I fired up Activity Monitor and force-killed the "cfprefsd" process. Be careful: there are multiple processes with this name running and you only want to kill the one running under your own user; do not kill the one running as root.

Doing this seems to flush the preferences cache and on the next run of my app, I get a pristine start-from-scratch launch.

Edit: As reported below, using defaults delete [your bundle identifier] at the command line also appears to eliminate the caching issue. I've had mixed success with this.

Answer 2

I found out that killing the user process cfprefsd will reflush the cache, so your changes will be kept

killall -u $USER cfprefsd