How can you add the Keyboards option in the settings of an app?
Like such: 
I know the Siri & Search keys you must enter in your Info.plist, but I wasn't able to find how to directly add the keyboards option.
The purpose is to be able to turn on a custom keyboard from the apps settings rather than going through General > Keyboards > Add Keyboard.
If the answer is "You can not", how can you add a keyboard from within the app's own settings. There are several keyboard applications out there that have this feature, so unless it's a private deal with Apple I'm sure there is a way to do this.
