1：
StandardTouchDelegate协议，
@protocol CCStandardTouchDelegate <NSObject>
@optional
- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesCancelled:(NSSet *)touches withEvent:(UIEvent*)event;
@end
此协议用于实现多点触控，原理是EAGLView继承自UIView，继承了touch的四个方法，而cocos2d在director绑定了EAGLView：
EAGLView *glView = [EAGLView viewWithFrame:[window bounds]
pixelFormat:kEAGLColorFormatRGB565 // kEAGLColorFormatRGBA8
depthFormat:0 // GL_DEPTH_COMPONENT16_OES
];
// attach the openglView to the director
[director setOpenGLView:glView];
2：接受多个触控点，必须在入口处调用
[viewController.view setMultipleTouchEnabled:YES];
否则只能接受单点。
layer在init时isTouchEnabled必须设置为yes，此方法会调用registerWithTouchDispatcher，将layer注册到TouchDelegate。
3：mac机上实验多点触控，只能测试到两个点：
option ＋ 点击
option ＋ shift 实现平移
