Where to apply for an airport transit visa?

My place of residence My visa application should be submitted to
Nigeria  Embassy of Switzerland in Abuja 
Chad see Representation agreement below 
Niger  see Representation agreement below 

Representation agreement

If a State does not have its proper visa section in a country or region, the delivery of a Schengen visa can be delegated to another Schengen State member with an agreement between both countries concerned.

The agreement allows the appointed representation to represent and handle Schengen visa applications within its own competence without consulting the other represented State.

Country / Region Schengen State which represents Switzerland My visa application should be submitted to
Chad  France  Embassy of France in N'Djamena 
Niger   Spain   Embassy of Spain in Niamey