Didbegincontact Is Being Called Multiple Times for the Same Skphysicsbody

Why are didBeginContact called multiple times?

I had the same problem (score increasing multiple times for a single enemy destroyed and multiple life points being lost for a single instance of damage.) A user on the Apple forums thinks that it's a bug in [SKPhysicsBody bodyWithTexture:size:] but I don't believe that's the case, because it was happening with other constructors too.

First off, the categoryBitMask and contactTestBitMask are very important, obviously. Take a look at Apple's SpriteKit Physics Collisions sample code:

// Contacts are often a double dispatch problem; the effect you want is based on the type of both bodies in the contact. This sample this in a brute force way, by checking the types of each. A more complicated example might use methods on objects to perform the type checking.

// The contacts can appear in either order, and so normally you'd need to check
each against the other. In this example, the category types are well ordered, so
the code swaps the two bodies if they are out of order. This allows the code
to only test collisions once.

What I did to solve it was setting a flag after handling each condition. In my case, I was testing whether bodyA.node.parent was nil in didBeginContact, because I called removeFromParent() on the missile/enemy nodes to destroy them.

I think you should expect the event to fire multiple times and your code in there has to make sure it's processed only once.

iOS Swift didBeginContact not being called

It turned out to be a simple problem. In my original code I was setting parameters for the SKPhysicsBody detection frame like so:

let carBody = SKPhysicsBody(
rectangleOfSize: car.frame.size, center: car.position)

Similarly I was doing the same for the second node that I was testing physics collisions for.

Simply removing the 'centre:' parameters like so:

let carBody = SKPhysicsBody(rectangleOfSize: car.frame.size)

for the two sprite nodes solved the problem and the nodes now crash into each other and push themselves aside as expected.

Swift spritekit didbegincontact being called with delay

Your problem isn't things are being delayed, your problem is your bounding box is not where you think it is

use view.showPhysics = true to determine where your boxes are

once you realize they are in the wrong spots, go to this line

knight.physicsBody = SKPhysicsBody(rectangleOf: knight.size, center: knight.position)

and fix it

knight.physicsBody = SKPhysicsBody(rectangleOf: knight.size)

Do so for the rest of your bodies

SpriteKit didBeginContact not being called

You haven't added your physics body for coins

SKSpriteNode *coins = [SKSpriteNode spriteNodeWithColor:[UIColor yellowColor] size:CGSizeMake(4, 4)];
coins.name = @"coins";
coins.position = CGPointMake(self.coinX+80, ground.position.y + ground.frame.size.height/2 + obstacle.frame.size.height/2 + 25);

coins.physicsBody = [SKPhysicsBody bodyWith...//need code here

coins.physicsBody.categoryBitMask = coinCategory;
coins.physicsBody.dynamic = NO;
coins.physicsBody.collisionBitMask = 0;
SKAction *revolution = [SKAction rotateByAngle:M_PI_4*10 duration:3];
SKAction *repeatRotate = [SKAction repeatActionForever:revolution];
[coins runAction:repeatRotate];
[self.world addChild:coins];

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