Hi,

I'm trying to understand how I can catch keyboard inputs in a ui reliably.

When I place a textbox on a form, i need to tap it to make it accept keys.

My use case:

I have a bluetooth keyboard connected to the ipad. (Actually, it's a hardware barcode laser
scanner that acts like a bluetooth keyboard and types any number it scans)

My aim is to accept any number 0-9 and the enter key always, no matter where the focus is.
Whenever enter is recognised, I would then collect the typed number and so something with it.

When developing desktop programs, I can force focus to a textbox from
code, so I don't have to click on it and any scanned number will go in there.

What is the best approach in Pythonista?

I'd prefer not having a textbox at all - and just get all keypresses on a UI.

Hmm, it looks there's an older post about this here - with a good example.
https://forum.omz-software.com/topic/2049/possible-to-subclass-uiview-and-redefine-keycommands-property/7

UPDATE

The code linked works after minor changes (print, Python3)
While the example catches keys with a modifier, setting the modifier to 0
makes it possible to catch normal keys and it's possible to catch the
Enter key via chr(13).

So while this looks do-able, the question is if this is a good approach:

One problem with it is that I haven't found out how to trigger updates on
the main view from the function that collects the keys. In my example,
I'm trying to update a label on the view (form) with the number that is scanned.
I've looked at the ui examples, where there's a "sender.superview" that
allows to connect to the other elements of the view.
Here the keyboard control is added as a Subview to the main view, so that doesn't work.

you just want to use begin_editing() on your textfield or textview afte you present it. It not in the docs, so don't feel bad you missed it .

To set tab order requires a but more effort-- see:

https://forum.omz-software.com/topic/4562/set-next-field-for-tab/12

For your other question, you can either walk your way up and down the view heirarchy
sender.superview.superview['panel']['label5']
or, when you set up your textfield, or button, or whatever, you could add an attribute with some key piece of info

textfield=ui.Textfield()
mainview.addsubview(textfield)
textfield.target=label
textfield.action=textfieldaction
...
#elsewhere
def textfieldaction(sender):
   sender.target.title='hello'

alternatively, using a custom view class for your main view lets you access the mainview via self.

class myview(ui.View):
   def __init__(self):
      self.label =ui.Label()
      self.add_subview(self.label)
....
   def textfield_action(self, sender):
      seld.label.title='hello'

That way, there is one commin place for everything that any ui element needs to know.