Previous versions of IntelliJ and AppCode already have Xcode Keymap.
But recent versions doesn't have it. You can add the Xcode keymap from the previous version of IntelliJ by this script.
It's based on the Xcode keymap IntelliJ IDEA ships with: https://github.com/JetBrains/intellij-community/blob/master/platform/platform-resources/src/idea/Keymap_Xcode.xml
$ git clone https://github.com/Pitzcarraldo/IntelliJ-IDEA-Xcode-Keymap.git
$ cd ./IntelliJ-IDEA-Xcode-Keymap
$ ./install.sh