Note for GNOME Later than 3.6
1. libibus maybe compiled as a dependency of gnome, don't try to remove it
If you're using gentoo, try below steps to remove ibus:
add -i18n use flag to your make.conf, and run:
emerge --update --newuse --deep @world --ask
rebuild gnome-shell with -nls use flag
emerge -cav app-i18n/ibus
2. uninstall package that contains ibus-daemon on your system.
Or if you want to keep ibus installed (if you want to use fcitx you don't need ibus at all, for older gnome 3.6 you might also hit this bug, so you'd better remove it), run:
gsettings set org.gnome.settings-daemon.plugins.keyboard active false
as your current user.
3. If you are using fedora, make sure to use imsettings to select "Fcitx".