We give a different presentation of a recent bijection due to Chapuy and
Dol\k{e}ga for nonorientable bipartite quadrangulations and we extend it to the
case of nonorientable general maps. This can be seen as a Bouttier--Di
Francesco--Guitter-like generalization of the Cori--Vauquelin--Schaeffer
bijection in the context of general nonorientable surfaces. In the particular
case of triangulations, the encoding objects take a particularly simple form
and this allows us to recover a famous asymptotic enumeration formula found by
Gao