Type ahead issue with UIKeyInput

Question

I have a controller that is taking custom key input and displaying it in a unique way. It becomes the key responder and implements UIKeyInput.

https://developer.apple.com/reference/uikit/uikeyinput

It was implemented in 8.0, before the typeahead functionality on the iOS keyboard. I am updating it for 10.0 and it's not managing the interaction well.

- (void)deleteBackward {
  NSString *text = self.codedLabel.text;

  if (text.length > 0) {
    text = [text substringToIndex:text.length-1];
  }

  self.codedLabel.text = text;
  self.decodeLabel.text = [text stringByReplacingOccurrencesOfString:@"\n" withString:@" | "];
  [self saveText:text];
}

- (BOOL)hasText {
  NSString *text = self.codedLabel.text;
  return (text.length > 0);
}

- (void)insertText:(NSString *)newtext {
  NSString *text = self.codedLabel.text;

  text = [text stringByAppendingString:newtext];
  self.codedLabel.text = text;
  self.decodeLabel.text = [text stringByReplacingOccurrencesOfString:@"\n" withString:@" | "];
  [self saveText:text];
}

When one of the type ahead words is selected, insertText: is invoked, but the newtext value is always 0xa000000000000201 and the debug output is

(lldb) po newtext


(lldb) p newtext.length
(NSUInteger) $1 = 1