macOS 10.14 use pmset to control graphic card switch.

graphic_card_switch_control.sh

# I find this https://discussions.apple.com/thread/8160651
# but it not match my 2018 version MacBook with macos 10.14
#
# On my local, gpuswitch value is 
# 0 -> does not use dedicated graphics
# 1 -> use dedicated graphics
# 2 -> switch automaticly (I guess), because 2 is default value when "automatic graphics switching" selected
#      in energy in preference.

# check settings depended on charger/battery
pmset -g custom

# let system use dedicated graphics card when charger plugin
sudo pmset -c gpuswitch 1

# let system use graphics card auto switch when using battery
sudo pmset -b gpuswitch 2

# let system use auto switch on charger/battery (my default setting)
sudo pmset -a gpuswitch 2