In case of Firebase CPP SDK >= 8.0.0, there was no control of futures returned from SDK code. So the correctness was not guaranteed.
In case of Firebase CPP SDK >= 8.0.0, no need to give up if Google Play Services is not available. They could be updating, for example, SDK defines a set of reasons and supports its API anyway. So let it decide.
Initial 500 ms delay has been removed from the initialization workflow: QTimer::singleShot(500 -> 0, ...).
Added new property fetching.
Added new signals googlePlayServicesError and futuresError.
Pooling future's status on timer is not an elegant and efficient solution, I used callbacks.
Support of Firebase CPP SDK < 8.0.0 has been kept.
Backward compatibility of QtFirebase API has been kept.
Hello!
QTimer::singleShot(500 -> 0, ...)
.fetching
.googlePlayServicesError
andfuturesError
.