在触摸屏幕的时候，触摸点的位置是十分重要的信息。得到的位置坐标是和它所处的试图或窗口相关的坐标。调用触摸对象的locationInView：方法即可，查找到触摸点在指定视图上的位置，就把视图对象传递进去。对自定义视图对象来说，这里调用[touch locationInView:self.view]来获得触摸在本视图上的位置。如果指定为nil，则返回触摸点在窗口的位置。

CGPoint originalLocation;   //全局变量 用于存储起始位置-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    UITouch *touch = [touches   anyObject];    originalLocation = [touch locationInView:self.view];    }-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{    UITouch *touch = [touches anyObject];    CGPoint currentLocation = [touch locationInView:self.view];    CGRect frame = self.view.frame;    frame.origin.x += currentLocation.x - originalLocation.x;    frame.origin.y += currentLocation.y - originalLocation.y;        self.view.frame = frame;  }