SpriteKit and programmatically draw simple graphics - swift

Question

Any suggestion on using SpriteKit rendering engine, but have the ability to draw game graphic programmatically. Those graphics are simple but slightly complex than just rectangular and oval.
I recently found out the SKShapeNode have a cap on the complexity when using custom path. I basically have a function that take a number to generate random CGPath shape, The larger the number the more complex and details about the shape. When I use a small number, there is no problem, but when I use a larger number to generate more complex path, SKShapeNode give me this error. (I tested on real device with iOS9.2.1 as well)
Assertion failed: (length + offset <= _length)
Related Question
Now I don't think using SKShapeNode is a good idea, so any suggestion on programmatically draw graphics that able to work nicely with SpriteKit?
I read somewhere else which is draw using the any graphics API available as long as it can convert to a format that SKTexture can initialize, is the right way to go?

Answer 1

If you will use SKTexture you can draw your chart with CGContext.
First of all you need create array of chart's points like:
let pathPoints: [CGPoint] = [...]
Then you need to call UIGraphicsBeginImageContext(rect.size) where rect.size is CGSize object which determines the size of the region in which will be inscribed the chart and rect is CGRect object. Next step is creation of CGContextRef and it setting:
UIGraphicsBeginImageContext(size)
let context: CGContextRef = UIGraphicsGetCurrentContext()!
CGContextSetStrokeColorWithColor(context, UIColor.redColor().CGColor);
CGContextSetLineWidth(context, lineWidth)
where lineWidth is CGFloat type value.
After this you can create your chart in context like this:
if pathPoints.count > 1 {
CGContextMoveToPoint(context, pathPoints.first!.x, pathPoints.first!.y)
for var i = 1; i < pathPoints.count; ++i {
CGContextAddLineToPoint(context, pathPoints[i].x, pathPoints[i].y)
}
}
CGContextStrokePath(context)
Then you need to create image form context like this:
let image = UIGraphicsGetImageFromCurrentImageContext()
Then create texture form image and use it for SKSpriteNode object that will be added to the scene:
let pathTexture = SKTexture(image: image)
let pathNode = SKSpriteNode(texture: pathTexture)
pathNode.position = CGPointMake(rect.origin.x + rect.width/2 - lineWidth/2, rect.origin.y + rect.height/2 - lineWidth/2)
pathNode.zPosition = 0
someParrentNodeThatOnScene.addChild(pathNode)
UIGraphicsEndImageContext()
That's all you need to create chart.