I used to append using
splineseries->append(i.key().toMSecsSinceEpoch(),i.value());
But x axis getting same value repeated .
splineseries->append(i.key().toMSecsSinceEpoch(),i.value());
will work . But We have set min and max values for DateTimeaxis like
Xaxis->setMin(QDateTime(QDate(2018,01,01),QTime(01,00,00)));
Xaxis->setMax(QDateTime(QDate(2050,01,03),QTime(12,00,00)));