重写父控件中的方法：(两个方法任选其一：)

    - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event;
    - (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event;

具体实现：

1. 方法一：
   //返回需要响应事件的view位置
   - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
   UIView *view = [super hitTest:point withEvent:event];
   if (view == nil) {
   //转换坐标系
   CGPoint newPoint = [self.thirdBtn convertPoint:point fromView:self];
   //判断触摸点是否在button上
   if (CGRectContainsPoint(self.thirdBtn.bounds, newPoint)) {
   view = self.thirdBtn;
   }
   //NSLog(@"point:%@ : newPoint:%@",NSStringFromCGPoint(point),NSStringFromCGPoint(newPoint));
   }
   return view;
   }
2. 方法二：
   //当point在父控件和子控件包含的区域时，应该返回YES，否则为NO；
   - (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
   NSLog(@"point:%@",NSStringFromCGPoint(point));
   if (!CGRectContainsPoint(self.bounds, point)) {
   //转换坐标系
   CGPoint newPoint = [self convertPoint:point toView:self.secondBtn];
   //NSLog(@"newPoit:%@",NSStringFromCGPoint(newPoint));
   //判断触摸点是否在secondBtn上
   if (CGRectContainsPoint(self.secondBtn.bounds, newPoint)) {
   return YES;
   }
   return NO;
   }
   return YES;
   }

难点：

1. 判断一个点是否在某个范围内

• CGRectContainsPoint(Rect, Point); //判断Rect中是否包含Point

• CGRectContainsRect(Rect1,Rect2);//判断Rect1中是否包含Rect2

2. 实现对控制点坐标系的转换

    `view1:视图一` `view2:视图二` 
    `point:view1坐标系中的点` `newPoint：新得到view2坐标系中的点`
    //将point从view1的坐标系中转换到view2的坐标系中得到newPoint
    CGPoint newPoint = [view2 convertPoint:point fromView:view1];
    CGPoint newPoint = [view1 convertPoint:point toView:view2];
    类似方法：
    - (CGRect)convertRect:(CGRect)rect toView:(nullable UIView *)view;
    - (CGRect)convertRect:(CGRect)rect fromView:(nullable UIView *)view;