Handling dial like rotation on CCNode by using UIPanGestureRecognizer

gistfile1.m

//! for gesture recognizer support in cocos2d use https://github.com/krzysztofzablocki/CCNode-SFGestureRecognizers
- (void)handlePanGesture:(UIPanGestureRecognizer*)gestureRecognizer
{
    CGPoint location = [[CCDirector sharedDirector] convertToGL:[gestureRecognizer locationInView:gestureRecognizer.view]];
    static CGPoint oldLocation;
    
    //! this will make sure that oldLocation is initialized
    if (gestureRecognizer.state != UIGestureRecognizerStateBegan) {
        //! we need to calculate angle difference between previous position and current one in regards to dial center
        CGPoint firstDir = ccpSub(oldLocation, dial.position);
        CGPoint secondDir = ccpSub(location, dial.position);
        
        prevAngle = -ccpToAngle(firstDir);
        curAngle = -ccpToAngle(secondDir);
        
        angleChange = CC_RADIANS_TO_DEGREES(curAngle - prevAngle);

        dial.rotation += angleChange;
    }
    oldLocation = location;
}