How to combine a physics body with tile sprites? - cocos2d-iphone

Question

I am working with tile map and box2d with cocos2D in the game for iOS, i want to move the tile with respect to physics bodies, i.e. to combine one or more tiles in a body and on contact if body is moving then tile sprites should also move. Please suggest something to do so.

Answer 1

You could use a CCPhysicsSprite for this.
The following code is from the default Box2D project in Cocos2d v2.
-(void) addNewSpriteAtPosition:(CGPoint)p
{
CCLOG(#"Add sprite %0.2f x %02.f",p.x,p.y);
// Define the dynamic body.
//Set up a 1m squared box in the physics world
b2BodyDef bodyDef;
bodyDef.type = b2_dynamicBody;
bodyDef.position.Set(p.x/PTM_RATIO, p.y/PTM_RATIO);
b2Body *body = world->CreateBody(&bodyDef);
// Define another box shape for our dynamic body.
b2PolygonShape dynamicBox;
dynamicBox.SetAsBox(.5f, .5f);//These are mid points for our 1m box
// Define the dynamic body fixture.
b2FixtureDef fixtureDef;
fixtureDef.shape = &dynamicBox;
fixtureDef.density = 1.0f;
fixtureDef.friction = 0.3f;
body->CreateFixture(&fixtureDef);
CCNode *parent = [self getChildByTag:kTagParentNode];
//We have a 64x64 sprite sheet with 4 different 32x32 images. The following code is
//just randomly picking one of the images
int idx = (CCRANDOM_0_1() > .5 ? 0:1);
int idy = (CCRANDOM_0_1() > .5 ? 0:1);
CCPhysicsSprite *sprite = [CCPhysicsSprite spriteWithTexture:spriteTexture_ rect:CGRectMake(32 * idx,32 * idy,32,32)];
[parent addChild:sprite];
[sprite setPTMRatio:PTM_RATIO];
[sprite setB2Body:body];
[sprite setPosition: ccp( p.x, p.y)];
}
NOTE The position of the sprite has been set after the body has been created. If you do it the other way around, you may get an exception. See here.