获取当前手指

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [super touchesBegan:touches withEvent:event];
    //获取当前点
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:self.superview];
    NSLog(@"%.2f, %.2f", point.x, point.y);

}