Turning off detection between sprites - sprite-kit

Question

I have two phyicsbodies in my spritekit game which are colliding and I am having a little difficulty getting them to stop.
I am posting the physics code for them below.
Problem is when the swarm touches my coins it pushes it, not exactly sure why since as far as my know my enemy is told to only contact with the player and my coin is told to only contact with the wall and the player (correct me if im wrong)
(P.S I commented out the collisionBitMask for the coin because when I dont my coins fall thru my walls )
Thanks
1St sprite
enemy = [SKSpriteNode spriteNodeWithImageNamed:#"Swarm"];
enemy.physicsBody =
[SKPhysicsBody bodyWithRectangleOfSize:enemy.size];
enemy.physicsBody.dynamic=NO;
enemy.name=#"Eagle";
enemy.physicsBody.categoryBitMask = PCFallersCategory;
// enemy.physicsBody.collisionBitMask =
// PCPlayerCategory;
enemy.physicsBody.contactTestBitMask = PCPlayerCategory;
enemy.physicsBody.restitution=0;
enemy.physicsBody.friction=0;
2nd Sprite.
self.name = #"coin";
CGFloat minDiam = MIN(self.size.width, self.size.height);
minDiam = MAX(minDiam-8, 8);
self.physicsBody =
[SKPhysicsBody bodyWithCircleOfRadius:minDiam/2.0];
self.physicsBody.dynamic=YES;
self.physicsBody.restitution =0;
self.physicsBody.friction = 0;
self.physicsBody.linearDamping = 0;
self.physicsBody.categoryBitMask = PCCollectableCategotry;
//self.physicsBody.collisionBitMask =PCPlayerCategory;
self.physicsBody.contactTestBitMask = PCPlayerCategory|PCWallCategory;

Answer 1

You need to explicitly set the collisionBitMask to 0.
enemy.physicsBody.collisionBitMask = 0;
According to the documentation
When two physics bodies contact each other, a collision may occur.
This body’s collision mask is compared to the other body’s category
mask by performing a logical AND operation. If the result is a
non-zero value, then this body is affected by the collision. Each body
independently chooses whether it wants to be affected by the other
body. For example, you might use this to avoid collision calculations
that would make negligible changes to a body’s velocity.
The default value is 0xFFFFFFFF (all bits set).
This means that by default, an SKPhysicsBody is configured to collide with all objects.