collision detection in didbegincontact does not work - ios

Question

I want every spritenode the user creates come with a left and right edge bitmask. Other bitmasks work, but this one don't.
Below the method for creating a new spritenode, which is called in TouchesBegin
-(void)spawnBrick
{
brick = [[BrickNodeOne alloc] init];
brick.name = #"Brick";
NSArray *array = [self objectForKeyedSubscript:#"Brick"];
BrickNodeOne *oldBrick;
if ([array count] > 0) {
oldBrick = [array objectAtIndex:([array count]-1)];
}
brick.position = CGPointMake(brick.size.width / 2, (brick.size.height + oldBrick.position.y)-15);
brick.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(brick.size.width, brick.size.height)];
brick.physicsBody.categoryBitMask = kBrickCategory;
brick.physicsBody.contactTestBitMask = kCarCategory;
brick.physicsBody.collisionBitMask = 0;
[self addChild:brick];
SKAction *moveTo = [SKAction moveByX:0.0 y:-125.0 duration:1.0];
[brick runAction:[SKAction repeatActionForever:moveTo]withKey:#"moveDown"];
_brickRightEdge = [[SKNode alloc] init];
_brickRightEdge.physicsBody = [SKPhysicsBody bodyWithEdgeFromPoint:CGPointMake(brick.size.width, 0.0) toPoint:CGPointMake(brick.size.width, brick.size.height)];
_brickRightEdge.physicsBody.dynamic = NO;
_brickRightEdge.physicsBody.categoryBitMask = brickRightEdgeCategory;
_brickRightEdge.physicsBody.contactTestBitMask = kCarCategory;
_brickRightEdge.position = brick.position;
[brick addChild:_brickRightEdge];
_brickLeftEdge = [[SKNode alloc] init];
_brickLeftEdge.physicsBody = [SKPhysicsBody bodyWithEdgeFromPoint:CGPointMake(0.0, 0.0) toPoint:CGPointMake(0.0, brick.size.height)];
_brickLeftEdge.physicsBody.dynamic = NO;
_brickLeftEdge.position = brick.position;
_brickLeftEdge.physicsBody.categoryBitMask = brickLeftEdgeCategory;
_brickLeftEdge.physicsBody.contactTestBitMask = kCarCategory;
[brick addChild:_brickLeftEdge];
}
The car spritenode which I want collision detection with the brick right and left edge is declared in didMoveToView
SKSpriteNode *car = [SKSpriteNode spriteNodeWithImageNamed:#"HighWayCar_Red"];
car.position = CGPointMake(self.size.width / 2, 120);
car.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:car.size];
car.physicsBody.categoryBitMask = kCarCategory;
car.physicsBody.contactTestBitMask = kWaterCategory | brickLeftEdgeCategory | brickRightEdgeCategory;
car.physicsBody.collisionBitMask = 0;
car.physicsBody.dynamic = NO;
car.zPosition = 2;
[self addChild:car];
Code DidBeginContact
if (firstBody.categoryBitMask == kCarCategory && secondBody.categoryBitMask == brickLeftEdgeCategory) {
NSLog(#"HIT");
}
if (firstBody.categoryBitMask == kCarCategory && secondBody.categoryBitMask == brickRightEdgeCategory) {
NSLog(#"HIT");
}
Update for comment
I declared `SKPhysicsContactDelegate` in the header file. Set the delegate in `didMoveToView`
Bitmasks:
static const uint32_t kBrickCategory = 0x1 << 0;
static const uint32_t leftEdgeCategory = 0x1 << 1;
static const uint32_t rightEdgeCategory = 0x1 << 2;
static const uint32_t brickLeftEdgeCategory = 0x1 << 3;
static const uint32_t brickRightEdgeCategory = 0x1 << 4;
static const uint32_t kCarCategory = 0x1 << 5;
static const uint32_t kWaterCategory = 0x1 << 6;