If you use Autocomplete's detached mode on an iPhone, you may notice that the first tap on the Autocomplete searchBox doesn't open the keyboard but the second tap does.
This a known issue related to the fact that iPhones don't let you programmatically assign focus:
AutoComplete can successfully set focus within a user event callback, but it can't open the keyboard. The keyboard only opens when the user deliberately taps the input (which cannot be simulated).
We've investigated this behavior, and we can't currently work around it without introducing a hack. This hack forces us to change how we schedule DOM updates, which would have unintended side-effects (such as reopening the search modal on close when the query has been updated).
As this is intentional browser behavior and there's currently not a clean workaround/solution, we have closed the issue.