CustomKeyboard | A custom keyboard extension written in Swift 5 | Keyboard library

I'm new to Swift and SwiftUI (and programming in general).

I'm trying to build an app about statistics, and because of these specific needs, I had to write a custom keyboard with numbers and basic operations. The problem is that I want to store the X values and Y values in two different arrays so I have to call my "ChartKeyboard" two times: one for writing the X values and other time for the Y values. Here is the code I use to call the keyboard:

I've just created an in-app custom keyboard, got through all the difficult stuff, but am now stumped on (what is probably trivial):

how to connect the buttons of a XIB and its associated class so that the appropriate text is entered into a UITextView on a viewController.

I created a XIB with a keyboard so that I can reuse the same keyboard in different controllers. Set all the constraints, classes, file owner, etc. Everything works perfectly - except for getting data from the key to the view.

Here is what I have:

I've just created an in-app custom keyboard by placing a bunch of buttons in a XIB (so that I can reuse it in different controllers) but am stumped on (what is probably trivial):

how to connect the buttons of the XIB so that when I press one the appropriate text is entered at the cursor location in a UITextView on a viewController. (For example, if 5 is pressed, a 5 should be entered at the current cursor location in the UITextView.)

Everything works perfectly - except for getting data from the key to the view.

I do not want to create any extension that will require the user enabling it in Settings. I'd also like to place the keyboard where I want, in particular to restrict it to half the screen when the phone is rotated into Landscape.

Here is what I have:

I am trying to present a custom keyboard that I built in an xib file, when I instantiate the class I need to pass some variables to that class in order to make things work correctly, but I am getting this error: Instance member 'target' cannot be used on type 'CustomKeyboardView'

on the lines