[IOS]hitTest的作用与用法【转】

hitTest的作用:当在一个view上添加一个屏蔽罩，但又不影响对下面view的操作，也就是可以透过屏蔽罩对下面的view进行操作，这个函数就很好用了。

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hitTest的用法：将下面的函数添加到UIView的子类中，也就是屏蔽罩类中即可。

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-(id)hitTest:(CGPoint)point withEvent:(UIEvent<wbr>*)event<wbr><wbr></wbr></wbr></wbr>

{

<wbr><wbr><wbr><wbr><wbr><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(126,34,172)">UIView</span><wbr>*hitView = [<span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">super</span><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(73,0,132)">hitTest</span>:point<wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(73,0,132)">withEvent</span>:event];</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">if</span><wbr>(hitView ==<wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">self</span>)</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr>{</wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">return</span><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">nil</span>;</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr>}</wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">else</span><wbr><wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr>{</wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><span style="word-wrap:normal; word-break:normal; line-height:24px; color:rgb(208,0,162)">return</span><wbr>hitView;</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>

<wbr><wbr><wbr><wbr><wbr><wbr>}</wbr></wbr></wbr></wbr></wbr></wbr>

}

转自：http://blog.sina.com.cn/s/blog_446da0320100yw9u.html

另外转一个相关的文章：

UiViewtouch事件传递

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

{

}

<wbr><wbr>这个函数的用处是判断当前的点击或者触摸事件的点是否在当前的view中。</wbr></wbr>

<wbr><wbr>它被hitTest:withEvent:调用，通过对每个子视图调用pointInside:withEvent:决定最终哪个视图来响应此事件。如果 PointInside:withEvent:返回YES，然后子视图的继承树就会被遍历（遍历顺序中最先响应的为：与用户最接近的那个视图。 it starts from the top-levelsubview），即子视图的子视图继续调用递归这个函数，直到找到可以响应的子视图（这个子视图的hitTest:withEvent:会返回self，而不是nil）；否则，视图的继承树就会被忽略。</wbr></wbr>

<wbr><wbr>当我们需要重写某个UIView的继承类UIViewInherit的时候，如果需要重写hitTest:withEvent:方法，就会出现是否调用[super hitTest:withEvent:]方法的疑问？究竟是否需要都是看具体需求，这里只是说明调与不调的效果。</wbr></wbr>

<wbr><wbr>如果不调用，那么重写的方法hitTest:withEvent:只会调用重写后的代码，根据所重写的代码返回self或nil，如果返回self那么你的这个UIViewInherit类会接受你的按键，然后调用touches系列方法；否则返回nil那么传递给UIViewInherit类的按键到此为止，它不接受它的父view给它的按键，即不会调用touches系列方法。这时，PointInside:withEvent:几乎没有作用。</wbr></wbr>

<wbr><wbr>如果调用，那么[super hitTest:withEvent:]方法首先是根据PointInside:withEvent:的返回值决定是否递归调用所有子View的hitTest:withEvent:方法。对于子View的hitTest:withEvent:方法调用也是一样的过程，这样一直递归下去，直到最先找到的某个递归层次上的子View的hitTest:withEvent:方法返回非nil，这时候，调用即结束，最终会调用这个子View的touches系列方法。</wbr></wbr>

<wbr></wbr>

<wbr><wbr><wbr>如果我们不想让某个视图响应事件，只需要重载 PointInside:withEvent:方法，让此方法返回NO就行了。不过从这里，还是不能了解到hitTest:WithEvent的方法的用途。</wbr></wbr></wbr>

http://blog.sina.com.cn/s/blog_87bed3110100t5cf.html

http://blog.csdn.net/iefreer/article/details/4754482

hitTest:withEvent:调用过程

The implementation of hitTest:withEvent: in UIResponder does the following:

It calls pointInside:withEvent: of self

If the return is NO, hitTest:withEvent: returns nil. the end of the story.

If the return is YES, it sends hitTest:withEvent: messages to its subviews. it starts from the top-level subview, and continues to other views until a subview returns a non-nil object, or all subviews receive the message.

If a subview returnsa non-nil object in thefirst time, the first hitTest:withEvent: returns that object. the end of the story.

If no subview returns anon-nilobject, the first hitTest:withEvent: returns self

This process repeats recursively, so normally the leafview of the view hierarchy is returned eventually.

However, you might override hitTest:withEvent to do something differently. Inmany cases, overriding pointInside:withEvent: is simpler and still provides enough options to tweak event handling in your application.