I do a lot of scientific writing. I would like to create a keyboard or two that contain characters I need to write. For example, I use the Greek keyboard a lot, but there are many other symbols in Unicode that I would like to use in my writing, and creating a custom keyboard seems to be the solution.
All instructions on creating custom keyboards usually come back to using XCode or Swift. I do not want to have to use a laptop or desktop to create a keyboard; I would like to do all this work on my iPhone, or occasionally on my iPad, and share the keyboards between my iPhone and iPad. I have found a version of Swift that downloads to my iPhone, but have no idea how to proceed from there. Note that I have decades of experience as a programmer, but I need a way to get started quickly by creating simple keyboards that encode Unicode characters, and don't want to spend a lot of time searching for how to do this. What tutorial should I read to find how to create a keyboard in, say, less than an hour, using only my iPhone and nothing else? What do I read to see how to share this keyboard with my iPad?