Physicsbody doesn't adhere to node's anchor point

Question

My scene has a bunch of rectangles with physics bodies that are the same size as the rectangle. I like to anchor all of my objects to CGPointZero, however I\'ve noticed when

Answer 1

I wrote this to fix Apple's lack thereof:

use pathForRectangleOfSize:withAnchorPoint: to replace your call to bodyWithRectangleOfSize: whose brief documentation tells us the problem: "Creates a rectangular physics body centered on the owning node’s origin."

@implementation SKPhysicsBody (CWAdditions)

+ (CGPathRef)pathForRectangleOfSize:(CGSize)size withAnchorPoint:(CGPoint)anchor {
  CGPathRef path = CGPathCreateWithRect( CGRectMake(-size.width * anchor.x, -size.height * anchor.y,
                                                    size.width,   size.height), nil);
  return path;
}

+ (SKPhysicsBody *)bodyWithRectangleOfSize:(CGSize)size withAnchorPoint:(CGPoint)anchor {
  CGPathRef path = [self pathForRectangleOfSize:size withAnchorPoint:anchor];
  return [self bodyWithPolygonFromPath:path];
}

@end

Edit: There is a new API in 7.1 to provide for this oversight.

+ (SKPhysicsBody *)bodyWithRectangleOfSize:(CGSize)s center:(CGPoint)center