QApplication::focusWidget() and QApplication::focusObject()

What’s the difference other than the return type? In addition, in my app the focusWidget() is returning 0 and focusObject() is returning an object to QML textinput. How can that be that both are not returning a pointer? I am using Qt5 and earlier in Qt4.8 focusWidget() used to work OK. I am trying to use QApplication::sendEvent with focusWidget() return value as the first parameter but it crashes because focusWidget() returns 0. If I use focusObject() then the keyEvent is not delivered.