Drawing dashed line in Sprite Kit using SKShapeNode and CGPath - ios

Question

I want to draw a dashed line in my sprite kit game, I can use SKShapeNode node to draw a normal line like the following:
UIBezierPath *_path=[UIBezierPath bezierPath];
//1
CGPoint point1 = CGPointMake(100,100);
CGPoint point2 = CGPointMake(150,150);
[_path moveToPoint:point1];
[_path addLineToPoint:point2];
//2
SKShapeNode *line = [SKShapeNode node];
line.path = _path.CGPath;
I tried to set a dashed pattern to UIBezierPath like this:
// adding this code at location 1 or 2 above but no effect
CGFloat dashes[] = {6, 2};
[_path setLineDash:dashes count:2 phase:0];
but the dashed pattern is not applied.
I also tried to create a dashed copy of CGPath directly from UIBezierpath.CGPath property as:
CGFloat dashes[] = {6, 2};
CGPathRef aCGPath= CGPathCreateCopyByDashingPath(_path.CGPath,NULL,0,dashes,2);
line.path = aCGPath;
but also the same.
I really appreciate if someone could explain what is the problem and how can I draw a dashed line between two points by applying dashed cgpath to skshapenode.
Edit: I know for this simple example I could divide the distance between these two points to small fixed distances and moving and drawing dashed line by bezeirpath but consider a free hand path with points came from touches, it is a very complex and inefficient to redraw the path with fixed length points then draw dashes. I wonder if there is a way to apply the dashed pattern to the path and making skshapenode to use it that is my question.

Answer 1

If anyone is still interested in a simple answer to this question:
Use CGPathCreateCopyByDashingPath to create a dashed copy of - [UIBezierCurve CGPath]
CGPathRef CGPathCreateCopyByDashingPath(
CGPathRef path,
const CGAffineTransform *transform,
CGFloat phase,
const CGFloat *lengths,
size_t count
);
and add it to the SKShapeNode's path property.
Example:
// creates a dashed pattern
CGFloat pattern[2];
pattern[0] = 10.0;
pattern[1] = 10.0;
CGPathRef dashed =
CGPathCreateCopyByDashingPath([bezierPath CGPath],
NULL,
0,
pattern,
2);
self.myShapeNode.path = dashed;
CGPathRelease(dashed);
EDIT: For performance, you can add an SKShapeNode to an SKEffectNode and set the shouldRasterize property to YES.

Answer 2

Change the code at location 1 to something like this:
UIBezierPath *_path=[UIBezierPath bezierPath];
CGPoint point1 = CGPointMake(100,100);
CGPoint point2 = CGPointMake(150,150);
CGFloat deltaX = 1;
CGFloat deltaY = 1;
CGPoint tmpPoint = point1;
[_path moveToPoint:point1];
while(tmpPoint.x<point2.x && tmpPoint.y<point2.y){
tmpPoint.x+=deltaX;
tmpPoint.y+=deltaY;
if((tmpPoint.y-point1.y)%2==1){
[_path addLineToPoint:tmpPoint];
}else{
[_path moveToPoint:tmpPoint];
}
}
// If the line is not a 45 degree straight line
// Please modify the while loop accordingly
[_path addLineToPoint:point2];