Pulling this out of the pull request #5963 as it is a very limited scope issue, impacting only in-app keyboard, not system keyboard, on iOS.

I have reproduced this issue myself.

Test start-of-sentence detection

• IOS: FAILED Tested with iOS 15.0. mostly

  • In-app

    • It should set the keyboard to the Shift layer at the start of a text field, after full stop (.), exclamation (!) or question mark (?) and one or spaces (e.g. . ).

      Not working! In iOS 15.0, there are two tabs audibly heard right after opening the Keyman app before the "Get Started" window appears. Click on "Done" to close the window to see the default layer of the keyboard instead of the shift layer. See the screenshot below.

      

      The shift layer appears only after tapping in the text area.

      

      Here is a screen recording for a better visual.

      Screen.Recording.2021-12-13.at.2.06.58.PM.mov

      In iOS 13.7, still hear the two taps, but no "Get Started" page is shown. The keyboard layout does show the shift layer right off.

      

    • It should keep the keyboard in the numeric layer after typing a digit, but move back to base layer for all other symbols.

      Not working! Pressing any key on the numeric layer moves the keyboard back to the default layer.

    • It should keep the keyboard in the shift layer after typing two capital letters (note that this is a temporary testing behaviour until we support a CAPS layer in an upcoming PR).

      Not working! The keyboard doesn't stay on shift layer after typing two capital letters in a row.

      

    Note that the default layer is shown when the Keyman app is opened from standby. It is expected to have shift layer shown instead.

    Screen.Recording.2021-12-13.at.1.07.16.PM.mov

    After a line break (pressing Enter key), the shift layer should be shown, but it still stays in the default layer. Please consider adding this as a new functionality.

Originally posted by @MakaraSok in #5963 (comment)