-(void)didBeginContact is not being called. Thoughts? - objective-c

Question

#import "collisionTestMyScene.h"
const static int nodeBitMask = 0x1 << 0;
const static int node1BitMask = 0x1 << 1;;
#implementation collisionTestMyScene
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
/* Setup your scene here */
self.physicsWorld.contactDelegate = self;
w = 0;
}
return self;
}
-(void) didBeginContact:(SKPhysicsContact *)contact {
NSLog(#"Contact Begin");
if (contact.bodyA.categoryBitMask == nodeBitMask) {
NSLog(#"Node is Body A");
}
if (contact.bodyA.categoryBitMask == node1BitMask) {
NSLog(#"Node is Body B");
}
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
/* Called when a touch begins */
for (UITouch *touch in touches) {
CGPoint location = [touch locationInNode:self];
node = [SKSpriteNode spriteNodeWithImageNamed:#"block.jpg"];
node.position = location;
[node setScale:0.07];
node.physicsBody.contactTestBitMask = node1BitMask;
node.physicsBody.categoryBitMask = nodeBitMask;
node.physicsBody.collisionBitMask = nodeBitMask;
//node.physicsBody.collisionBitMask = 0;
node1 = [SKSpriteNode spriteNodeWithImageNamed:#"block2.jpg"];
node1.position = CGPointMake(200, 200);
node1.physicsBody.categoryBitMask = node1BitMask;
node1.physicsBody.contactTestBitMask = nodeBitMask;
node1.physicsBody.collisionBitMask = node1BitMask;
//node1.physicsBody.collisionBitMask = 0;
[node1 setScale:0.07];
[self addChild:node];
[self addChild:node1];
node.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(node.size.width, node.size.height)];
node1.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(node1.size.width, node1.size.height)];
SKAction *moveUp = [SKAction moveToX:100 duration:3];
node1.physicsBody.affectedByGravity = NO;
node.physicsBody.affectedByGravity = NO;
[node1 runAction:moveUp];
w = 1;
}
}
It is never NSLogging anything. I have tried changing the bit masks, and more. The CGRectIntersects function would work, however it is not accurate enough. Also, the two nodes are in perfect box shapes. What could I be doing wrong? Thank you in advance!

Answer 1

The problem here are the bit masks. The two nodes are in different category, contact and collision groups (bit masks). Therefore they will not contact nor collide because the bitmasks are compared with AND and only if the result is non-zero will the contact/collision occur.
In short, put them in the same contact bit mask at the least, in order to receive didBeginContact messages.