On OSX, how do I gradient fill a path stroke?

Question

Using the plethora of drawing functions in Cocoa or Quartz it\'s rather easy to draw paths, and fill them using a gradient. I can\'t seem to find an acceptable way however,

Answer 1

According to Peter Hosey's answer I've managed to do a simple gradient curve, which looks like this:

I've done this in drawRect(_:) method of UIView class by writing the code below:

override func drawRect(rect: CGRect) {
    let context = UIGraphicsGetCurrentContext()

    CGContextBeginTransparencyLayer (context, nil)
    let path = createCurvePath()
    UIColor.blueColor().setStroke()
    path.stroke()
    CGContextSetBlendMode(context, .SourceIn)

    let colors          = [UIColor.blueColor().CGColor, UIColor.redColor().CGColor]
    let colorSpace      = CGColorSpaceCreateDeviceRGB()
    let colorLocations  :[CGFloat] = [0.0, 1.0]
    let gradient        = CGGradientCreateWithColors(colorSpace, colors, colorLocations)
    let startPoint      = CGPoint(x: 0.0, y: rect.size.height / 2)
    let endPoint        = CGPoint(x: rect.size.width, y: rect.size.height / 2)

    CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, CGGradientDrawingOptions.DrawsBeforeStartLocation)
    CGContextEndTransparencyLayer(context)
}

Function createCurvePath() returns an UIBezierPath object. I've also set path.lineWidth to 5 points.