feat(ios): Support for Bluetooth / external keyboard in Keyman for iPhone and iPad

[MakaraSok]

Describe the bug

Keyman stable doesn't output the expected characters of the keyboard selected off of the keyboard menu both in-app and as a system keyboard. See the screen recording below.

https://user-images.githubusercontent.com/28331388/173553424-3e819a6d-4ac2-4efa-ad5e-7ce755a06022.mov

This behavior doesn't occur in Android.

---

Keyman for iPhone/iPad/Android:

• Device: iPad mini 6
• OS: iOS 15.5
• Keyman version: 14.0.288-stable
• Target application: Keyman and Notes

[jahorton]

Sadly, this is due to a system limitation. 3rd party keyboards on Apple devices are not allowed to receive physical keystroke events. While we could do this in-app, this would create an expectation for users that we would be unable to fill.

So, until Apple changes that policy... it's out of our hands.

[mcdurdin]

While we could do this in-app, this would create an expectation for users that we would be unable to fill.

I think there would be value in this, particularly for 3rd party apps that embed a Keyman keyboard such as the App Builders. Something to consider. Then if and when Apple get their act together, it's hopefully a small step to enable it for the system keyboard too.

[mcdurdin]

See also #1018, #6071.

[MayuraVerma]

please check this article https://developer.apple.com/documentation/uikit/mac_catalyst/handling_key_presses_made_on_a_physical_keyboard

https://developer.apple.com/forums/thread/18122

below is a comment in the above thread. I have not verified the claim.

No I don't, but I recently was told that GBoard and SwiftKey can be used with iPad Pro Smart Keyboard. I don't own an iPad Pro so I couldn't test it. However, I did test with my iPad Air with Apple Bluetooth Keyboard and it doesn't work. I have been search the web for this and no luck for now... If anyone knows this, please kindly reply.

[mcdurdin]

That's a very old thread that I've seen before -- the claim isn't correct as far as I know.

[MayuraVerma]

I should have checked the dates before commenting!

I myself had verified, that hardware keyboards do not work with iPad Pro in Dec 2021 in #6071

[mcdurdin]

Moving to Future milestone as I suggest we implement in-app support.

[mcdurdin]

https://community.software.sil.org/t/keyman-not-working-with-new-magic-keyboard-for-ipad-pro-2024/8781/2

[Meng-Heng]

One more user who encounters this issue: https://community.software.sil.org/t/i-have-installed-the-keyman-app-for-ipad-however-while-using-my-bluetooth-keyboard-it-doesn-t-render-indic/9081/1

[Meng-Heng]