UIBezierPath pulse animation - calayer

Question

I'm drawing a UIBezierPath on a UIScrollView I have made an animation that draws the path from start to end point but this is not the animation that I want.
UIBezierPath *linePath = [UIBezierPath bezierPath];
[linePath moveToPoint:startPoints];
[linePath addLineToPoint:endPoints;
//shape layer for the line
CAShapeLayer *line = [CAShapeLayer layer];
line.path = [linePath CGPath];
// line.fillColor = [[UIColor blackColor] CGColor];
line.strokeColor = [[colors objectAtIndex:i] CGColor];
line.lineWidth = 5;
// line.contents = (id)[[UIImage imageNamed:#"Mask.png"] CGImage];
// line.contentsGravity = kCAGravityCenter;
CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
pathAnimation.duration = 3.0;
pathAnimation.fromValue = #(0.0f);
pathAnimation.toValue = #(1.0f);
pathAnimation.repeatCount = HUGE_VAL;
[line addAnimation:pathAnimation forKey:#"strokeEnd"];
I have tried adding a contents to the shape layer but I'm bad at animations. The effect I want to achieve is the same animation as "slide to unlock" has, or a path that pulses.
I've tried to do the same thing as the answer from slide-to-unlock but can't seem to manage

Answer 1

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"];