Question

I want to be able to enable multitouch for cocos2d. How can I do this? I want to test each touch event like my code below. Please help.

-(void) ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

UITouch *myTouch = [touches anyObject];
CGPoint location = [myTouch locationInView:[myTouch view]];
location = [[CCDirector sharedDirector] convertToGL:location];
b2Vec2 locationWorld = b2Vec2(location.x/PTM_RATIO, location.y/PTM_RATIO);
CGSize screenSize = [CCDirector sharedDirector].winSize;

if (locationWorld.x >= screenSize.width*2/5/PTM_RATIO && locationWorld.x <= screenSize.width*3.25/5/PTM_RATIO) {
    cannonballTouch1 = 1;
    float force = 6;
    b2Vec2 direction = cannonballBody->GetWorldCenter() - cannonBody->GetWorldCenter();
    b2Vec2 iforce = b2Vec2(1.0f/direction.x * force, 1.0f/direction.y * force);
    NSLog(@"%.2f", direction.y);
    NSLog(@"%.2f", iforce.y);
    b2Vec2 force1 = b2Vec2(0, iforce.y);
    cannonballBody->ApplyLinearImpulse(force1, cannonballBody->GetPosition());
}
if (locationWorld.x > screenSize.width*3.25/5/PTM_RATIO) {
    cannonballTouch2 = 1;
    float force = 6;
    b2Vec2 direction = cannonballBody2->GetWorldCenter() - cannonBody2->GetWorldCenter();
    b2Vec2 iforce = b2Vec2(1.0f/direction.x * force, 1.0f/direction.y * force);
    NSLog(@"%.2f", direction.y);
    NSLog(@"%.2f", iforce.y);
    b2Vec2 force1 = b2Vec2(0, iforce.y);
    cannonballBody2->ApplyLinearImpulse(force1, cannonballBody2->GetPosition());
}
}

Answer 1

this page discribe it pretty well.

http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/MultitouchEvents/MultitouchEvents.html

To handle multitouch events, you must first create a subclass of a responder class. This subclass could be any one of the following:

A custom view (subclass of UIView)
A subclass of UIViewController or one of its UIKit subclasses
A subclass of a UIKit view or control class, such as UIImageView or UISlider
A subclass of UIApplication or UIWindow (although this would be rare)
A view controller typically receives, via the responder chain, touch events initially sent to its view if that view does not override the touch-handling methods.

For instances of your subclass to receive multitouch events, your subclass must implement one or more of the UIResponder methods for touch-event handling, described below. In addition, the view must be visible (neither transparent or hidden) and must have its userInteractionEnabled property set to YES, which is the default.

The following sections describe the touch-event handling methods, describe approaches for handling common gestures, show an example of a responder object that handles a complex sequence of multitouch events, discuss event forwarding, and suggest some techniques for event handling.