Merge selected feature pyqgis

Question

I want to merge the selected features. I found this post but I can not do it.
Can anybody help me?

layer = iface.activeLayer()
obj1 = 24
obj2= 25
expr = QgsExpression( " \"ID_PARCEL\" = '{}' OR \"ID_PARCEL\"='{}' ".format(obj1,obj2))
it = layer.getFeatures( QgsFeatureRequest( expr ) )
ids = [i.id() for i in it]
if ids == []:
    print 'ERROR - WAS NOT FOUND'
else:
    layer.setSelectedFeatures( ids )
    selectFeatures = layer.selectedFeatures()

#MERGE SELECTED FEATURES

Answer 1

Try something like this below

geom = None
for feat in selectFeatures:
    if geom == None:
       geom = feat.geometry()
    else:
       geom = geom.combine(feat.geometry())