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.
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.
I found out that killing the user process cfprefsd will reflush the cache, so your changes will be kept
killall -u $USER cfprefsd
In terminal:
defaults delete com.somecompany.someapp
BTW, I've just released a GUI app that may be more convenient than working with the defaults command:
http://www.tempel.org/PrefsEditor
It works practically the same as Xcode's plist editor, but affects the user's app preferences directly.
To delete all your prefs, you could open your prefs in my Prefs Editor, Select All, then delete them with the Backspace or Delete key, and they're instantly all gone.
However, for this particular task, using defaults delete might still be quicker, especially if you put the command into a text file ending in ".command", and make it executable (with chmod +x). Then you can double click it from the Finder to execute it.
来源：https://stackoverflow.com/questions/19303958/deleting-plist-file-does-not-reset-app-on-macos-10-9