title: Pause SpriteKit game with Physics SKSpriteNode child
body: <p>I have a SKSpriteNode with a dynamic physics body on a <code>SKNode *_fgLayer</code>.</p>
  
  <p>Now, when I pause or unpause the game I want that SKSpriteNode to remain in place and not rotate or fall down. If I simply use <code>_fgLayer.paused = YES;</code> the SKSpriteNode does not stay in place but rather rotates and falls down. If I set <code>physicsBody.dynamic = NO;</code> when paused and         <code>physicsBody.dynamic = YES;</code> when unpaused it works. </p>
  
  <p>However, after a few tries I always get the following crash: </p>
  
  <p><code>"Assertion failed: (typeA == b2_dynamicBody || typeB == b2_dynamicBody), function SolveTOI, file /SourceCache/PhysicsKit/PhysicsKit-4.6/PhysicsKit/Box2D/Dynamics/b2World.cpp, line 670."</code></p>
  
  <p>So, I guess setting a <code>physicsBody.dynamic = NO;</code> and back does not work.</p>
  
  <p>Does anyone have an idea of<br>
  <strong>how to pause dynamic physics bodies to remain in place when the game is paused?</strong></p>