Sprite Kit How to change physics body programatically

Question

How can I change a sprite's physics body programatically? Here's what I'm doing:

[mySprite removeFromParent];
mySprite.physicsBody = [MySprite body2];
// body setup
[myContainer addChild: mySprite];

But somehow it just doesn't work. What am I doing wrong?

EDIT: Here's my hero character, he's composed of 3 bodies

1. feet - larger circle as a feet sensor
2. polygon - the one I want to flip horizontally
3. smaller circle - it is there pinned to the polygon so that the textures follow the other bodies

Answer 1

You can mirror the sprite like this :

mySprite.xScale = -1; // assuming the scale desired is indeed 1.

I believe that you can do the same with a SKShapeNode, so you can do the same with your physics body.