Path not visible under UIGraphicsBeginImageContextWithOptions - SpriteKit - ios

Question

I'm drawing a path in my SKScene to show the track of my object.
Everything works fine, I can draw the path for all points and add it to scene.
The problem happens when I try to printscreen my scene, everything appears but the path.
Where am i doing it wrong?
- (void)drawPathTrackBall
{
// length of my nsmutablearray with the object track
NSUInteger len = [_trackBallPath count];
// start image context
CGRect bounds = self.scene.view.bounds;
UIGraphicsBeginImageContextWithOptions(bounds.size, YES, [UIScreen mainScreen].scale);
[self.view drawViewHierarchyInRect:bounds afterScreenUpdates:YES];
// draw my path
SKShapeNode *line = [[SKShapeNode alloc] init];
CGMutablePathRef linePath = CGPathCreateMutable();
CGPathMoveToPoint(linePath, NULL, _ballStartX, _ballStartY);
for(NSUInteger i=0; i<len; ++i)
{
NSValue *nsPoint = [_trackBallPath objectAtIndex:i];
CGPoint p = nsPoint.CGPointValue;
CGPathAddLineToPoint(linePath, NULL, p.x, p.y);
}
line.path = linePath;
line.lineWidth = 0.5f;
line.strokeColor = [UIColor redColor];
[_container addChild:line];
_screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
Thanx

Answer 1

First of all - you're creating simple path, its not connected or drawed to somewhere in your code to context. I didn't learn SpriteKit yet, but I know CoreGraphics well and I think you just can't simply use there SpriteKit API to create a screenshot. Instead try to use native CoreGraphics methods.
To make your code work you need:
Obtain context to which you will draw.
As you've already created a path - just add it to context.
Then stroke/fill it.
To obtain current context to draw call: CGContextRef ctx = UIGraphicsGetCurrentContext();
To add path use : CGContextAddPath(ctx, path);
To stroke/fill use CGContextStrokePath(ctx); / CGContextFillPath(ctx);
So your updated code should look like(notice I've removed code related to SpriteKit stuff):
- (void)drawPathTrackBall
{
// length of my nsmutablearray with the object track
NSUInteger len = [_trackBallPath count];
// start image context
CGRect bounds = self.scene.view.bounds;
UIGraphicsBeginImageContextWithOptions(bounds.size, YES, [UIScreen mainScreen].scale);
[self.view drawViewHierarchyInRect:bounds afterScreenUpdates:YES];
CGContextRef ctx = UIGraphicsGetCurrentContext(); // Obtain context to draw.
CGMutablePathRef linePath = CGPathCreateMutable();
CGPathMoveToPoint(linePath, NULL, _ballStartX, _ballStartY);
for(NSUInteger i=0; i<len; ++i)
{
NSValue *nsPoint = [_trackBallPath objectAtIndex:i];
CGPoint p = nsPoint.CGPointValue;
CGPathAddLineToPoint(linePath, NULL, p.x, p.y);
}
// I've exchanged SpriteKit node API calls with CoreGraphics equivalents.
CGContextSetLineWidth(ctx, 0.5f);
CGContextSetStrokeColorWithColor(ctx, [UIColor redColor].CGColor);
CGContextAddPath(ctx, linePath);
CGContextStrokePath(ctx);
_screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
Try it.