Why is collision detection no longer working in cocos2d v3?

In old project i create collisions like in this question: why collision not working , cocos2d v3? . It ran ok, however when I created a new project something was wrong. I don't know what I did differently this time. Please help me.

-(void)addAIAction:(int)i{
    if (!arrAI) {
        arrAI = [[NSMutableArray alloc]init];
    }
    CCSprite *sprite = [CCSprite spriteWithImageNamed:@"res/gu_button.png"];
    sprite.position = [GameConfig convertPoint:ccp(viewSize.width, 160)];
    sprite.physicsBody.collisionType=@"aiCollision";
    sprite.physicsBody = [CCPhysicsBody bodyWithCircleOfRadius:sprite.contentSize.width/2 andCenter:ccp(sprite.contentSize.width/2, sprite.contentSize.height/2)];
    sprite.physicsBody.type = CCPhysicsBodyTypeDynamic;
    [_physicsNode addChild:sprite];
    [arrAI addObject:sprite];
}

// -----------------------------------------------------------------------

-(void)update:(CCTime)delta{
    for (CCSprite *sp in arrPlayer) {
        sp.position= ccp(sp.position.x+playerSpeed, sp.position.y);
    }
    for (CCSprite *sp in arrAI) {
        sp.position= ccp(sp.position.x-aiSpeed, sp.position.y);
    }

implement delegate :

-(BOOL)ccPhysicsCollisionBegin:(CCPhysicsCollisionPair *)pair  playerCollision:(CCNode *)nodeA aiCollision:(CCNode *)nodeB{
    NSLog(@"Coll.");


- (id)init
{
    // Apple recommend assigning self with supers return value
    self = [super init];
    if (!self) return(nil);

    viewSize=CGSizeMake([GameConfig converPoint:480], [GameConfig converPoint:320]);
    _physicsNode = [CCPhysicsNode node];
    _physicsNode.collisionDelegate =self;
    _physicsNode.debugDraw =YES;
    _physicsNode.gravity=ccp(0, 0);

please let me know why " ccPhysicsCollisionBegin " never call thanks everyone

You've given no evidence to say your setting the delegate for the physics body, so therefore the ccPhysicsCollisionBegin method may not be called.

I don't know V3, but I'm guessing your going to need to add:

sprite.phisicsBody.deligate = self;

before you call [_physicsNode addChild:sprite]; in your addAIAction:.