[CCPhysicsBody eachArbiter:] fix and unit tests.

Former-commit-id: 9393904

Author: slembcke

UnitTests/CCPhysicsTests.m

@@ -731,6 +731,45 @@ -(void)testBodyTypeCollisions
 	[physicsNode onExit];
 }
 
+-(void)testBodyEachCollisionPair
+{
+	CCPhysicsNode *physicsNode = [CCPhysicsNode node];
+	physicsNode.gravity = ccp(0, -100);
+	
+	CCNode *node1 = [CCNode node];
+	node1.physicsBody = [CCPhysicsBody bodyWithCircleOfRadius:1.0 andCenter:CGPointZero];
+	node1.physicsBody.type = CCPhysicsBodyTypeStatic;
+	[physicsNode addChild:node1];
+	
+	CCNode *node2 = [CCNode node];
+	node2.position = ccp(0, 10);
+	node2.physicsBody = [CCPhysicsBody bodyWithCircleOfRadius:1.0 andCenter:CGPointZero];
+	node2.physicsBody.type = CCPhysicsBodyTypeDynamic;
+	[physicsNode addChild:node2];
+	
+	// Force entering the scene to set up the physics objects.
+	[physicsNode onEnter];
+	
+	// Step the physics for a while.
+	for(int i=0; i<100; i++){
+		[physicsNode fixedUpdate:1.0/100.0];
+	}
+	
+	__block BOOL check = NO;
+	
+	[node1.physicsBody eachCollisionPair:^(CCPhysicsCollisionPair *pair) {
+		CCPhysicsShape *a, *b; [pair shapeA:&a shapeB:&b];
+		check = (
+			(a.node == node1 && b.node == node2) ||
+			(b.node == node1 && a.node == node2)
+		);
+	}];
+	
+	XCTAssert(check, @"The objects should have had a collision pair listed between them.");
+	
+	[physicsNode onExit];
+}
+
 // TODO
 // * Check that body and shape settings are preserved through multiple add/remove cycles and are actually applied to the cpBody.
 // * Check that changing properties before and after adding to an active physics node updates the properties correctly.

cocos2d/CCPhysicsBody.m

@@ -281,8 +281,6 @@ -(void)eachCollisionPair:(void (^)(CCPhysicsCollisionPair *))block
 		pair.arbiter = arbiter;
 		block(pair);
 	});
-	
-	pair.arbiter = NULL;
 }
 
 //MARK: Velocity

cocos2d/CCPhysicsNode.m

@@ -48,6 +48,7 @@ @implementation CCPhysicsCollisionPair {
 }
 
 -(cpArbiter *)arbiter {return _arbiter;}
+-(void)setArbiter:(cpArbiter *)arbiter {_arbiter = arbiter;}
 
 // Check that the arbiter is set and return it.
 -(cpArbiter *)arb