Draw gradient along a curved UIBezierPath

In an app, I draw a curved UIBezierPath an an MKOverlayPathView class to show flight routes. This is the code I am using:

- (UIBezierPath *)pathForOverlayForMapRect:(MKMapRect)mapRect {

    ... bla bla bla ...

    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:s];
    [path addQuadCurveToPoint:e controlPoint:cp1];
    [path addLineToPoint:e2];
    [path addQuadCurveToPoint:s2 controlPoint:cp2];
    [path closePath];

    return path;   
  }

- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context{

    self.mapRect = mapRect;

    CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 1.0);
    CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 1.0);
    CGContextSetLineWidth(context, mapRect.size.height/700);
    CGContextSetLineJoin(context, kCGLineJoinRound);
    CGContextSetLineCap(context, kCGLineCapRound);

    CGContextAddPath(context, [self pathForOverlayForMapRect:mapRect].CGPath);

    [self updateTouchablePathForMapRect:mapRect];

    CGContextDrawPath(context, kCGPathFillStroke);

}

This is working just fine but I would like to draw a gradient along that path instead of just a fill color. And this is where it is starting to get very tricky.

I have experimented with CGContextDrawLinearGradient() but it hasn't got me anywhere useful yet.