  We study the strong magnetic field limit for a nonlinear Iwatsuka-type model,
i.e. a nonlinear Schr\"odinger equation in two spatial dimensions with a
magnetic vector potential that only depends on the $x$-coordinate. Using a
high-frequency averaging technique, we show that this equation can be
effectively described by a nonlocal nonlinear model, which is no longer
dispersive. We also prove that, in this asymptotic regime, inhomogeneous
nonlinearities are confined along the $y$-axis.
