iphone - 触摸移动时图像旋转很慢

Question

我编写了一个程序，可以根据需要旋转我的 imageView（CW 或 ~CW）。它工作正常。但它响应非常慢，我希望它快速响应...你能帮我解决这个问题吗？提前致谢...！

以下是我的代码------------

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

        UITouch * touch = [[event allTouches]anyObject];
        CGPoint prevLoc = [touch previousLocationInView:self];
        CGPoint loc = [touch locationInView:self];

        if (isRotating) {

            float prevAngle = atan2(prevLoc.y-self.center.y,
                                    prevLoc.x-self.center.x);

            float newAngle = atan2( loc.y-self.center.y,
                                  loc.x-self.center.x);
            float finalAngle =angle+(newAngle-prevAngle);


            //Apply new transform
            CGAffineTransform rotateTransform = CGAffineTransformMakeRotation(Angle);

            self.transform=rotateTransform;
            angle = finalAngle;

        }
    }