Need SpriteKit collision to occur only on first contact

Question

I currently have two nodes in use, one of which is a boat (polygon) and the other a straight vertical rectangle. The boat needs to be a polygon so that it can be hit via projectiles, however this causes me problems when it collides with the vertical rectangle due to the many sides it's coming into contact with. Hence a piece of code I want ran only once is instead ran multiple times.

Is there anyway to make the collision detection only function for the first contact so that it doesn't repeatedly call?

I'm aware of setting the categoryBitMask to 0 however doing so renders the boat unable to be hit by anything else- something I don't want. Additionally I considered using a boolean variable to only run the code once whilst the boat is passing through, however as previously mentioned, due to the different sides, the code think it's passed through when in fact it's just hitting another side of the boat.

I don't have much code to show here other than setting physics bodies so I don't think it's necessary, but inside didBeginContact() I'm using a categoryBitMask comparison to check for collisions.

I may have not explained this very well, in which case I apologize, my English is not the best!

If anyone can help, it'd be much appreciated, thanks.

Answer 1

You can combine the individual physics bodies of your ship into a single body with

+ (SKPhysicsBody *)bodyWithBodies:(NSArray *)bodies

and then test for contacts with the composite body instead of the individual components.

Answer 2

If you are subclassing your node then simply create a BOOL property for it.

BOOL alreadyHit;

If you are not subclassing, use the SKNode's userData dictionary and create an entry for the same.