I ended up dooing this:
UIBezierPath *linePath = [UIBezierPath bezierPath];
[linePath moveToPoint:startPoints];
[linePath addLineToPoint:endPoints];
//gradient layer for the line
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = CGRectMake(0, 0, 150.0, 1.0);
gradient.cornerRadius = 5.0f;
gradient.startPoint = CGPointMake(0.0, 0.5);
gradient.endPoint = CGPointMake(1.0, 0.5);
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor clearColor] CGColor],(id)[[UIColor whiteColor] CGColor],(id)[[UIColor blueColor] CGColor],(id)[[UIColor clearColor] CGColor], nil];
[scrollViewContent.layer addSublayer:gradient];
CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"position"];
anim.path = [linePath CGPath];
anim.rotationMode = kCAAnimationRotateAuto;
anim.repeatCount = 0;
anim.duration = 1;
[gradient addAnimation:anim forKey:@"gradient"];