SKPhysicsWorld bodyWithTexture not working well with complex shapes - ios

Am I the only one whose having issues with the new bodyWithTexture function of SKPhysicsBody?
I'm new to iOS development and maybe it's me, but I'm trying to create a game where I need to detect if a ball is inside a path.
I'm loading both from images dynamically (as the level proceeds the paths are more and more complex), and I'm setting a physics body to both the ball (bodyWithCircle) and from the dynamic path which is a PNG file of a path and all the rest is transparent background. I'm using the new bodyWithTexture function (yes I know it's supported only under iOS 8), and after assigning bit masks I've defined a contact between the ball and path and am informed with begin/end contact.
SKSpriteNode *lvlPath = [SKSpriteNode spriteNodeWithImageNamed:currentLevel.imagePath];
lvlPath.position = CGPointMake(self.frame.size.width/2, self.frame.size.height/2);
lvlPath.physicsBody = [SKPhysicsBody bodyWithTexture:lvlPath.texture size:lvlPath.frame.size];
now for simple paths like straight line, it works great. once it comes to complicated paths - the mechanism is going crazy, at least in my simluator (running iOS 8).
i've created another simple app just to check this issue, and saw that it's going crazy when the path is a complex shape. when the ball enters the path in one direction it seems to be working (begin/end contact), but going the reverse direction suddenly acts weird when still inside the path it reports to have ended contact, and then like randomly flips begin/end contact.
help... since the levels are loaded dynamically, this is a really cool feature for me, saving me the definitions of all levels as CGPathRef and creating a polygon for each level (and perhaps device).
thanks all,
Eyal
edit
example screenshot:
https://www.dropbox.com/s/e8v9g1kajtvakfq/screenshot%20bodywithtexture.jpg?dl=0
in this example the ball with the arrow is inited using bodyWithCircle, and the C shaped object is inited using bodyWithTexture. I'm debug printing "didBeginContact" and "didEndContact" and it freaks out in the top line there, you can see it's with "didEndContact" while the two object are definitely at contact. If I jiggle it (I'm moving it with the cursor) it suddenly flips to "didBeginContact".
With Simpler objects (like horizontal/vertical lines with round corners) it works perfectly.

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I did find this which seems to solve that issue (although I have not tried it out).
https://gist.github.com/man1/413642637ebd0b00fe2b
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