Nikon manufactures two Wireless Adapters that you can use with some earlier model cameras to enable wireless downloading of images using their Mobile app.
The WU-1A and WU-1B are compatible with select models, and will not work with any other camera models.
DSLRs: Nikon Df, D7100, D5200, D3300, D3200.
Nikon 1: S2.
Coolpix: A, P7800, P530, P520, P330.
DSLRs: Nikon D610, D600
Nikon 1: V2, S1, J3, AW1.