blocks|key|280449|text|这似乎是一个很基本的问题。但我同意你的观点，这份文件不像其他文件那么清晰，所以我的答案是。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|280450|UIResponder中的hitTest:withEvent:实现如下所示：|offset|length|style|CODE|280451|它调用self|280452|If的pointInside:withEvent:，|unordered-list-item|280453|+is+NO，hitTest:withEvent:返回nil。故事的结尾。|280454|如果返回的结果是YES，它会将hitTest:withEvent:消息发送到它的子视图。它从顶层子视图开始，一直到其他视图，直到某个子视图返回非nil对象，或者所有子视图都收到消息。|280455|如果某个子视图第一次返回非nil对象，则第一个hitTest:withEvent:将返回该对象。故事的结尾。|280456|如果没有任何子视图返回非nil对象，则第一个hitTest:withEvent:返回|280457|280458|280459|280460|此过程会递归重复，因此通常最终会返回视图层次结构的叶视图。|280461|但是，您可能会重写hitTest:withEvent来做一些不同的事情。在许多情况下，重写pointInside:withEvent:更简单，并且仍然提供了足够的选项来调整应用程序中的事件处理。|280462|entityMap^0|0|D|I|0|3|4|0|3|M|0|7|I|R|3|0|F|I|20|3|0|D|3|N|I|0|C|3|M|I|0|0|0|0|0|9|H|19|M|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|14|8|@$D|15|E|16|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|17|8|@$D|18|E|19|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|1A|8|@$D|1B|E|1C|F|G]]|9|@]|A|$]]|$1|M|3|N|5|L|7|1D|8|@$D|1E|E|1F|F|G]|$D|1G|E|1H|F|G]]|9|@]|A|$]]|$1|O|3|P|5|L|7|1I|8|@$D|1J|E|1K|F|G]|$D|1L|E|1M|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|L|7|1N|8|@$D|1O|E|1P|F|G]|$D|1Q|E|1R|F|G]]|9|@]|A|$]]|$1|S|3|T|5|L|7|1S|8|@$D|1T|E|1U|F|G]|$D|1V|E|1W|F|G]]|9|@]|A|$]]|$1|U|3|-4|5|L|7|1X|8|@]|9|@]|A|$]]|$1|V|3|-4|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|X|3|Y|5|6|7|20|8|@]|9|@]|A|$]]|$1|Z|3|10|5|6|7|21|8|@$D|22|E|23|F|G]|$D|24|E|25|F|G]]|9|@]|A|$]]|$1|11|3|-4|5|6|7|26|8|@]|9|@]|A|$]]]|12|$]]

It seems quite a basic question. But I agree with you the document is not as clear as other documents, so here is my answer. 

The implementation of <code>hitTest:withEvent:</code> in UIResponder does the following:

<ul>
<li>It calls <code>pointInside:withEvent:</code> of <code>self</code></li>
<li>If the return is NO, <code>hitTest:withEvent:</code> returns <code>nil</code>. the end of the story.</li>
<li>If the return is YES, it sends <code>hitTest:withEvent:</code> messages to its subviews.
it starts from the top-level subview, and continues to other views until a subview
returns a non-<code>nil</code> object, or all subviews receive the message.</li>
<li>If a subview returns a non-<code>nil</code> object in the first time, the first <code>hitTest:withEvent:</code> returns that object. the end of the story.</li>
<li>If no subview returns a non-<code>nil</code> object, the first <code>hitTest:withEvent:</code> returns <code>self</code></li>
</ul>

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

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

blocks|key|280469|text|我认为你混淆了子类化和视图层次结构。医生说的内容如下。假设你有这样的视图层次结构。关于层次，我不是在谈论类层次，而是视图层次中的视图，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|280470|%2B----------------------------%2B
%7CA+++++++++++++++++++++++++++%7C
%7C%2B--------%2B+++%2B------------%2B+%7C
%7C%7CB+++++++%7C+++%7CC+++++++++++%7C+%7C
%7C%7C++++++++%7C+++%7C%2B----------%2B%7C+%7C
%7C%2B--------%2B+++%7C%7CD+++++++++%7C%7C+%7C
%7C+++++++++++++%7C%2B----------%2B%7C+%7C
%7C+++++++++++++%2B------------%2B+%7C
%2B----------------------------%2B|code-block|syntax|javascript|280471|假设你把手指放在D里面。下面是将要发生的事情：|offset|length|style|CODE|280472|在视图hierarchy.|280473|pointInside:withEvent:的最顶层视图A上调用|unordered-list-item|280474|hitTest:withEvent:，在每个视图上递归调用。|ordered-list-item|280475|pointInside:withEvent:在A上调用，returns+YES|280476|pointInside:withEvent:在B上调用，returns+YES|280477|pointInside:withEvent:在C上调用，returns+YES|280478|280479|在D上调用|280480|280481|​|280482|280483|在返回YES的视图上，它将向下查看层次结构，以查看发生触摸的子视图。在这种情况下，从A，C和D，它将是命中测试视图|280484|280485|entityMap^0|0|0|8|1|0|0|0|M|S|1|0|0|I|1|0|M|N|1|10|3|1|0|M|N|1|10|3|1|0|M|N|1|10|3|1|0|1|1|0|0|0|0|3|3|16|1|18|1|1A|1|0|0^^$0|@$1|2|3|4|5|6|7|1C|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1E|8|@$I|1F|J|1G|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|1H|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1I|8|@$I|1J|J|1K|K|L]|$I|1L|J|1M|K|L]]|9|@]|A|$]]|$1|R|3|S|5|T|7|1N|8|@$I|1O|J|1P|K|L]]|9|@]|A|$]]|$1|U|3|V|5|T|7|1Q|8|@$I|1R|J|1S|K|L]|$I|1T|J|1U|K|L]|$I|1V|J|1W|K|L]]|9|@]|A|$]]|$1|W|3|X|5|T|7|1X|8|@$I|1Y|J|1Z|K|L]|$I|20|J|21|K|L]|$I|22|J|23|K|L]]|9|@]|A|$]]|$1|Y|3|Z|5|T|7|24|8|@$I|25|J|26|K|L]|$I|27|J|28|K|L]|$I|29|J|2A|K|L]]|9|@]|A|$]]|$1|10|3|-4|5|6|7|2B|8|@]|9|@]|A|$]]|$1|11|3|12|5|6|7|2C|8|@$I|2D|J|2E|K|L]]|9|@]|A|$]]|$1|13|3|-4|5|6|7|2F|8|@]|9|@]|A|$]]|$1|14|3|15|5|6|7|2G|8|@]|9|@]|A|$]]|$1|16|3|-4|5|6|7|2H|8|@]|9|@]|A|$]]|$1|17|3|18|5|T|7|2I|8|@$I|2J|J|2K|K|L]|$I|2L|J|2M|K|L]|$I|2N|J|2O|K|L]|$I|2P|J|2Q|K|L]]|9|@]|A|$]]|$1|19|3|-4|5|6|7|2R|8|@]|9|@]|A|$]]|$1|1A|3|-4|5|6|7|2S|8|@]|9|@]|A|$]]]|1B|$]]

I think you are confusing subclassing with the view hierarchy. What the doc says is as follows. Say you have this view hierarchy. By hierarchy I'm not talking about class hierarchy, but views within views hierarchy, as follows:

<pre><code>+----------------------------+
|A |
|+--------+ +------------+ |
||B | |C | |
|| | |+----------+| |
|+--------+ ||D || |
| |+----------+| |
| +------------+ |
+----------------------------+
</code></pre>

Say you put your finger inside <code>D</code>. Here's what will happen:

<ol>
<li><code>hitTest:withEvent:</code> is called on <code>A</code>, the top-most view of the view hierarchy.</li>
<li><code>pointInside:withEvent:</code> is called recursively on each view.
<ol>
<li><code>pointInside:withEvent:</code> is called on <code>A</code>, and returns <code>YES</code></li>
<li><code>pointInside:withEvent:</code> is called on <code>B</code>, and returns <code>NO</code></li>
<li><code>pointInside:withEvent:</code> is called on <code>C</code>, and returns <code>YES</code></li>
<li><code>pointInside:withEvent:</code> is called on <code>D</code>, and returns <code>YES</code></li>
</ol></li>
<li>On the views that returned <code>YES</code>, it will look down on the hierarchy to see the subview where the touch took place. In this case, from <code>A</code>, <code>C</code> and <code>D</code>, it will be <code>D</code>.</li>
<li><code>D</code> will be the hit-test view</li>
</ol>

blocks|key|3204431|text|感谢你的回答，他们帮助我解决了“覆盖”视图的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3204432|%2B----------------------------%2B
%7CA+%2B--------%2B++++++++++++++++%7C
%7C++%7CB++%2B------------------%2B++%7C
%7C++%7C+++%7CC++++++++++++X++++%7C++%7C
%7C++%7C+++%2B------------------%2B++%7C
%7C++%7C++++++++%7C++++++++++++++++%7C
%7C++%2B--------%2B++++++++++++++++%7C+
%7C++++++++++++++++++++++++++++%7C
%2B----------------------------%2B|code-block|syntax|javascript|3204433|假设X+-用户的触摸。B上的pointInside:withEvent:返回NO，因此hitTest:withEvent:返回A。我在UIView上写了一个类别，当你需要在最可见的视图上接收触摸时，可以处理这个问题。|offset|length|style|CODE|3204434|-+(UIView+*)overlapHitTest:(CGPoint)point+withEvent:(UIEvent+*)event+{
++++//+1
++++if+(!self.userInteractionEnabled+%7C%7C+[self+isHidden]+%7C%7C+self.alpha+==+0)
++++++++return+nil;

++++//+2
++++UIView+*hitView+=+self;
++++if+(![self+pointInside:point+withEvent:event])+{
++++++++if+(self.clipsToBounds)+return+nil;
++++++++else+hitView+=+nil;
++++}

++++//+3
++++for+(UIView+*subview+in+[self.subviewsreverseObjectEnumerator])+{
++++++++CGPoint+insideSubview+=+[self+convertPoint:point+toView:subview];
++++++++UIView+*sview+=+[subview+overlapHitTest:insideSubview+withEvent:event];
++++++++if+(sview)+return+sview;
++++}

++++//+4
++++return+hitView;
}|3204435|我们不应该为隐藏或透明的视图发送触摸事件，或者将|3204436|设置为result.|unordered-list-item|3204437|
|3204438|Check+|3204439|+is+self，self将被递归地视为hit的所有子视图的潜在触摸。如果有，则返回它。|ordered-list-item|3204440|否则根据步骤2的结果返回self或nil。|3204441|3204442|3204443|注意，[self.subviewsreverseObjectEnumerator]需要遵循从上到下的视图层次结构。并检查clipsToBounds以确保不测试屏蔽子视图。|3204444|用法：|3204445|带有此|3204446|的子类view.|3204447|Replace+hitTest:withEvent:中的|3204448|导入类别|3204449|-+(UIView+*)hitTest:(CGPoint)point+withEvent:(UIEvent+*)event+{
++++return+[self+overlapHitTest:point+withEvent:event];
}|3204450|Official+Apple's+Guide也提供了一些很好的例子。|3204451|希望这对某些人有帮助。|3204452|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/event_delivery_responder_chain/event_delivery_responder_chain.html#//apple_ref/doc/uid/TP40009541-CH4-SW2^0|0|0|2|1|B|1|E|M|12|2|17|I|1R|1|1V|6|0|0|0|0|0|0|4|4|9|4|0|0|0|0|3|12|1O|D|0|0|0|0|8|I|0|0|0|0|M|0|0|0^^$0|@$1|2|3|4|5|6|7|1U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1W|8|@$I|1X|J|1Y|K|L]|$I|1Z|J|20|K|L]|$I|21|J|22|K|L]|$I|23|J|24|K|L]|$I|25|J|26|K|L]|$I|27|J|28|K|L]|$I|29|J|2A|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|2B|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|2C|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|2D|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|2E|8|@]|9|@]|A|$]]|$1|V|3|W|5|S|7|2F|8|@]|9|@]|A|$]]|$1|X|3|Y|5|Z|7|2G|8|@$I|2H|J|2I|K|L]|$I|2J|J|2K|K|L]]|9|@]|A|$]]|$1|10|3|11|5|Z|7|2L|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|2M|8|@]|9|@]|A|$]]|$1|13|3|-4|5|6|7|2N|8|@]|9|@]|A|$]]|$1|14|3|15|5|6|7|2O|8|@$I|2P|J|2Q|K|L]|$I|2R|J|2S|K|L]]|9|@]|A|$]]|$1|16|3|17|5|6|7|2T|8|@]|9|@]|A|$]]|$1|18|3|19|5|6|7|2U|8|@]|9|@]|A|$]]|$1|1A|3|1B|5|Z|7|2V|8|@]|9|@]|A|$]]|$1|1C|3|1D|5|Z|7|2W|8|@$I|2X|J|2Y|K|L]]|9|@]|A|$]]|$1|1E|3|1F|5|6|7|2Z|8|@]|9|@]|A|$]]|$1|1G|3|1H|5|D|7|30|8|@]|9|@]|A|$E|F]]|$1|1I|3|1J|5|6|7|31|8|@]|9|@$I|32|J|33|1|34]]|A|$]]|$1|1K|3|1L|5|6|7|35|8|@]|9|@]|A|$]]|$1|1M|3|-4|5|6|7|36|8|@]|9|@]|A|$]]]|1N|$1O|$5|1P|1Q|1R|A|$1S|1T]]]]

Thanks for answers, they helped me to solve situation with "overlay" views.

<pre><code>+----------------------------+
|A +--------+ |
| |B +------------------+ |
| | |C X | |
| | +------------------+ |
| | | |
| +--------+ | 
| |
+----------------------------+
</code></pre>

Assume <code>X</code> - user's touch. <code>pointInside:withEvent:</code> on <code>B</code> returns <code>NO</code>, so <code>hitTest:withEvent:</code> returns <code>A</code>. I wrote category on <code>UIView</code> to handle issue when you need to receive touch on top most visible view.

<pre><code>- (UIView *)overlapHitTest:(CGPoint)point withEvent:(UIEvent *)event {
 // 1
 if (!self.userInteractionEnabled || [self isHidden] || self.alpha == 0)
 return nil;

 // 2
 UIView *hitView = self;
 if (![self pointInside:point withEvent:event]) {
 if (self.clipsToBounds) return nil;
 else hitView = nil;
 }

 // 3
 for (UIView *subview in [self.subviewsreverseObjectEnumerator]) {
 CGPoint insideSubview = [self convertPoint:point toView:subview];
 UIView *sview = [subview overlapHitTest:insideSubview withEvent:event];
 if (sview) return sview;
 }

 // 4
 return hitView;
}
</code></pre>

<ol>
<li>We should not send touch events for hidden or transparent views, or views with <code>userInteractionEnabled</code> set to <code>NO</code>;</li>
<li>If touch is inside <code>self</code>, <code>self</code> will be considered as potential result.</li>
<li>Check recursively all subviews for hit. If any, return it.</li>
<li>Else return self or nil depending on result from step 2.</li>
</ol>

Note, <code>[self.subviewsreverseObjectEnumerator]</code> needed to follow view hierarchy from top most to bottom. And check for <code>clipsToBounds</code> to ensure not to test masked subviews.

Usage:

<ol>
<li>Import category in your subclassed view.</li>
<li>Replace <code>hitTest:withEvent:</code> with this</li>
</ol>

<pre class="lang-or-tag-here prettyprint-override"><code>- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
 return [self overlapHitTest:point withEvent:event];
}
</code></pre>

<a href="http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/event_delivery_responder_chain/event_delivery_responder_chain.html#//apple_ref/doc/uid/TP40009541-CH4-SW2" rel="noreferrer">Official Apple's Guide</a> provides some good illustrations too.

Hope this helps somebody.

blocks|key|278704|text|它显示的是这个代码片段！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|278705|-+(UIView+*)hitTest:(CGPoint)point+withEvent:(UIEvent+*)event
{
++++if+(self.hidden+%7C%7C+!self.userInteractionEnabled+%7C%7C+self.alpha+<+0.01)
++++{
++++++++return+nil;
++++}

++++if+(![self+pointInside:point+withEvent:event])
++++{
++++++++return+nil;
++++}

++++__block+UIView+*hitView+=+self;

++++[self.subViews+enumerateObjectsWithOptions:NSEnumerationReverse+usingBlock:%5E(id+obj,+NSUInteger+idx,+BOOL+*stop)+{+++

++++++++CGPoint+thePoint+=+[self+convertPoint:point+toView:obj];

++++++++UIView+*theSubHitView+=+[obj+hitTest:thePoint+withEvent:event];

++++++++if+(theSubHitView+!=+nil)
++++++++{
++++++++++++hitView+=+theSubHitView;

++++++++++++*stop+=+YES;
++++++++}

++++}];

++++return+hitView;
}|code-block|syntax|javascript|278706|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

It shows like this snippet!

<pre><code>- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
 if (self.hidden || !self.userInteractionEnabled || self.alpha &lt; 0.01)
 {
 return nil;
 }

 if (![self pointInside:point withEvent:event])
 {
 return nil;
 }

 __block UIView *hitView = self;

 [self.subViews enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id obj, NSUInteger idx, BOOL *stop) { 

 CGPoint thePoint = [self convertPoint:point toView:obj];

 UIView *theSubHitView = [obj hitTest:thePoint withEvent:event];

 if (theSubHitView != nil)
 {
 hitView = theSubHitView;

 *stop = YES;
 }

 }];

 return hitView;
}
</code></pre>

blocks|key|2990833|text|我发现这个Hit-Testing+in+iOS非常有帮助|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2990834|​|2990835|📷|atomic|2990836|2990837|-+(UIView+*)hitTest:(CGPoint)point+withEvent:(UIEvent+*)event+{
++++if+(!self.isUserInteractionEnabled+%7C%7C+self.isHidden+%7C%7C+self.alpha+<=+0.01)+{
++++++++return+nil;
++++}
++++if+([self+pointInside:point+withEvent:event])+{
++++++++for+(UIView+*subview+in+[self.subviews+reverseObjectEnumerator])+{
++++++++++++CGPoint+convertedPoint+=+[subview+convertPoint:point+fromView:self];
++++++++++++UIView+*hitTestView+=+[subview+hitTest:convertedPoint+withEvent:event];
++++++++++++if+(hitTestView)+{
++++++++++++++++return+hitTestView;
++++++++++++}
++++++++}
++++++++return+self;
++++}
++++return+nil;
}|code-block|syntax|javascript|2990838|编辑Swift+4:|style|BOLD|2990839|override+func+hitTest(_+point:+CGPoint,+with+event:+UIEvent?)+->+UIView?+{
++++if+self.point(inside:+point,+with:+event)+{
++++++++return+super.hitTest(point,+with:+event)
++++}
++++guard+isUserInteractionEnabled,+!isHidden,+alpha+>+0+else+{
++++++++return+nil
++++}

++++for+subview+in+subviews.reversed()+{
++++++++let+convertedPoint+=+subview.convert(point,+from:+self)
++++++++if+let+hitView+=+subview.hitTest(convertedPoint,+with:+event)+{
++++++++++++return+hitView
++++++++}
++++}
++++return+nil
}|2990840|entityMap|0|LINK|mutability|MUTABLE|url|http://smnh.me/hit-testing-in-ios/|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/bb3cf7d0adac11cfc22e0a9f15793b20.png|imageAlt^0|5|I|0|0|0|0|1|1|0|0|0|0|A|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@$A|19|B|1A|1|1B]]|C|$]]|$1|D|3|E|5|6|7|1C|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|1D|8|@]|9|@$A|1E|B|1F|1|1G]]|C|$]]|$1|I|3|E|5|6|7|1H|8|@]|9|@]|C|$]]|$1|J|3|K|5|L|7|1I|8|@]|9|@]|C|$M|N]]|$1|O|3|P|5|6|7|1J|8|@$A|1K|B|1L|Q|R]]|9|@]|C|$]]|$1|S|3|T|5|L|7|1M|8|@]|9|@]|C|$M|N]]|$1|U|3|-4|5|6|7|1N|8|@]|9|@]|C|$]]]|V|$W|$5|X|Y|Z|C|$10|11]]|12|$5|13|Y|14|C|$15|16|17|-4]]]]

I find this <a href="http://smnh.me/hit-testing-in-ios/" rel="noreferrer">Hit-Testing in iOS</a> to be very helpful

<img src="https://i.stack.imgur.com/FL27E.png" alt="enter image description here">

<pre><code>- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
 if (!self.isUserInteractionEnabled || self.isHidden || self.alpha &lt;= 0.01) {
 return nil;
 }
 if ([self pointInside:point withEvent:event]) {
 for (UIView *subview in [self.subviews reverseObjectEnumerator]) {
 CGPoint convertedPoint = [subview convertPoint:point fromView:self];
 UIView *hitTestView = [subview hitTest:convertedPoint withEvent:event];
 if (hitTestView) {
 return hitTestView;
 }
 }
 return self;
 }
 return nil;
}
</code></pre>

Edit Swift 4:

<pre><code>override func hitTest(_ point: CGPoint, with event: UIEvent?) -&gt; UIView? {
 if self.point(inside: point, with: event) {
 return super.hitTest(point, with: event)
 }
 guard isUserInteractionEnabled, !isHidden, alpha &gt; 0 else {
 return nil
 }

 for subview in subviews.reversed() {
 let convertedPoint = subview.convert(point, from: self)
 if let hitView = subview.hitTest(convertedPoint, with: event) {
 return hitView
 }
 }
 return nil
}
</code></pre>

blocks|key|2990851|text|@lion的代码片段就像是一种魔力。我将其移植到swift+2.1，并将其用作UIView的扩展。我把它贴在这里，以防有人需要它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2990852|extension+UIView+{
++++func+overlapHitTest(point:+CGPoint,+withEvent+event:+UIEvent?)+->+UIView?+{
++++++++//+1
++++++++if+!self.userInteractionEnabled+%7C%7C+self.hidden+%7C%7C+self.alpha+==+0+{
++++++++++++return+nil
++++++++}
++++++++//2
++++++++var+hitView:+UIView?+=+self
++++++++if+!self.pointInside(point,+withEvent:+event)+{
++++++++++++if+self.clipsToBounds+{
++++++++++++++++return+nil
++++++++++++}+else+{
++++++++++++++++hitView+=+nil
++++++++++++}
++++++++}
++++++++//3
++++++++for+subview+in+self.subviews.reverse()+{
++++++++++++let+insideSubview+=+self.convertPoint(point,+toView:+subview)
++++++++++++if+let+sview+=+subview.overlapHitTest(insideSubview,+withEvent:+event)+{
++++++++++++++++return+sview
++++++++++++}
++++++++}
++++++++return+hitView
++++}
}|code-block|syntax|javascript|2990853|要使用它，只需覆盖uiview中的hitTest:point:withEvent，如下所示：|2990854|override+func+hitTest(point:+CGPoint,+withEvent+event:+UIEvent?)+->+UIView?+{
++++let+uiview+=+super.hitTest(point,+withEvent:+event)
++++print("hittest",uiview)
++++return+overlapHitTest(point,+withEvent:+event)
}|2990855|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

The snippet of @lion works like a charm. I ported it to swift 2.1 and used it as an extension to UIView. I'm posting it here in case somebody needs it.

<pre><code>extension UIView {
 func overlapHitTest(point: CGPoint, withEvent event: UIEvent?) -&gt; UIView? {
 // 1
 if !self.userInteractionEnabled || self.hidden || self.alpha == 0 {
 return nil
 }
 //2
 var hitView: UIView? = self
 if !self.pointInside(point, withEvent: event) {
 if self.clipsToBounds {
 return nil
 } else {
 hitView = nil
 }
 }
 //3
 for subview in self.subviews.reverse() {
 let insideSubview = self.convertPoint(point, toView: subview)
 if let sview = subview.overlapHitTest(insideSubview, withEvent: event) {
 return sview
 }
 }
 return hitView
 }
}
</code></pre>

To use it, just override hitTest:point:withEvent in your uiview as follows:

<pre><code>override func hitTest(point: CGPoint, withEvent event: UIEvent?) -&gt; UIView? {
 let uiview = super.hitTest(point, withEvent: event)
 print("hittest",uiview)
 return overlapHitTest(point, withEvent: event)
}
</code></pre>

blocks|key|282310|text|1.+User+touch
2.+event+is+created
3.+hit+testing+by+coordinates+-+find+first+responder+-+UIView+and+successors+(UIWindow)+
+3.1+hit+testing+-+recursive+find+the+most+deep+view
++3.1.1+point+inside+-+check+coordinates
4.+Send+Touch+Event+to+the+First+Responder|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|282311|类图|unstyled|282312|📷|atomic|offset|length|282313|3命中测试|282314|Find+a+First+Responder|style|BOLD|CODE|282315|本例中的First+Responder是最深层的UIView+point()(hitTest()在内部使用point()+)方法，它返回true。它总是通过UIApplication+->+UIWindow+->+First+Responder|282316|func+hitTest(_+point:+CGPoint,+with+event:+UIEvent?)+->+UIView?
func+point(inside+point:+CGPoint,+with+event:+UIEvent?)+->+Bool|282317|在内部，hitTest()看起来像|282318|func+hitTest()+->+View?+{

++++if+(isUserInteractionEnabled+==+false+%7C%7C+isHidden+==+true+%7C%7C+alpha+==+0+%7C%7C+point()+==+false)+{+return+nil+}

++++for+subview+in+subviews+{
++++++++if+subview.hitTest()+!=+nil+{
++++++++++++return+subview
++++++++}
++++}
++++++++
++++return+nil

}|282319|4将触摸事件发送到First+Responder|282320|//UIApplication.shared.sendEvent()

//UIApplication,+UIWindow
func+sendEvent(_+event:+UIEvent)

//UIResponder
func+touchesBegan(_+touches:+Set<UITouch>,+with+event:+UIEvent?)
func+touchesMoved(_+touches:+Set<UITouch>,+with+event:+UIEvent?)
func+touchesEnded(_+touches:+Set<UITouch>,+with+event:+UIEvent?)
func+touchesCancelled(_+touches:+Set<UITouch>,+with+event:+UIEvent?)|282321|让我们来看一个例子|282322|​|282323|282324|282325|282326|响应器链|282327|它是一种chain+of+responsibility模式。它由能够处理UIEvent的UIResponser组成。在这种情况下，它从覆盖touch...的first+responder开始。super.touch...调用响应器链中的下一个环节|282328|282329|事件总线等addTarget或sendAction方法也使用Responder+chain|282330|//UIApplication.shared.sendAction()
func+sendAction(_+action:+Selector,+to+target:+Any?,+from+sender:+Any?,+for+event:+UIEvent?)+->+Bool|282331|看一看示例|282332|class+AppDelegate:+UIResponder,+UIApplicationDelegate+{
++++@objc
++++func+foo()+{
++++++++//this+method+is+called+using+Responder+Chain
++++++++print("foo")+//foo
++++}
}

class+ViewController:+UIViewController+{
++++func+send()+{
++++++++UIApplication.shared.sendAction(#selector(AppDelegate.foo),+to:+nil,+from:+view1,+for:+nil)
++++}
}|282333|*处理多点触控时会考虑isExclusiveTouch|282334|[Android+onTouch]|282335|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/b7f8c47b2a2f15a24bc44d1c1b679b6a.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/aa7e3339ff1841316483264797eb557e.png|2|https://ask.qcloudimg.com/http-save/yehe-900000/862ffcc73924d928ce045a22385819f8.jpeg|3|https://ask.qcloudimg.com/http-save/yehe-900000/26b521f61b4965f7803c3e17b2925346.png|4|LINK|MUTABLE|url|https://stackoverflow.com/a/57222691/4770877^0|0|0|0|1|0|0|0|0|6|7|F|7|F|0|4|F|O|6|V|7|13|9|1H|7|26|18|0|0|4|9|0|0|9|F|0|0|0|0|0|1|1|0|0|1|2|0|0|0|4|0|4|N|10|7|18|B|1X|8|2O|E|0|0|1|3|0|5|9|F|A|U|F|0|0|0|0|B|G|0|0|H|4|0^^$0|@$1|2|3|4|5|6|7|2C|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|2D|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|2E|8|@]|9|@$J|2F|K|2G|1|2H]]|A|$]]|$1|L|3|M|5|F|7|2I|8|@]|9|@]|A|$]]|$1|N|3|O|5|F|7|2J|8|@$J|2K|K|2L|P|Q]|$J|2M|K|2N|P|Q]|$J|2O|K|2P|P|R]]|9|@]|A|$]]|$1|S|3|T|5|F|7|2Q|8|@$J|2R|K|2S|P|R]|$J|2T|K|2U|P|R]|$J|2V|K|2W|P|R]|$J|2X|K|2Y|P|R]|$J|2Z|K|30|P|R]|$J|31|K|32|P|R]]|9|@]|A|$]]|$1|U|3|V|5|6|7|33|8|@]|9|@]|A|$B|C]]|$1|W|3|X|5|F|7|34|8|@$J|35|K|36|P|R]]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|37|8|@]|9|@]|A|$B|C]]|$1|10|3|11|5|F|7|38|8|@$J|39|K|3A|P|R]]|9|@]|A|$]]|$1|12|3|13|5|6|7|3B|8|@]|9|@]|A|$B|C]]|$1|14|3|15|5|F|7|3C|8|@]|9|@]|A|$]]|$1|16|3|17|5|F|7|3D|8|@]|9|@]|A|$]]|$1|18|3|H|5|I|7|3E|8|@]|9|@$J|3F|K|3G|1|3H]]|A|$]]|$1|19|3|H|5|I|7|3I|8|@]|9|@$J|3J|K|3K|1|3L]]|A|$]]|$1|1A|3|17|5|F|7|3M|8|@]|9|@]|A|$]]|$1|1B|3|1C|5|F|7|3N|8|@$J|3O|K|3P|P|Q]]|9|@]|A|$]]|$1|1D|3|1E|5|F|7|3Q|8|@$J|3R|K|3S|P|R]|$J|3T|K|3U|P|R]|$J|3V|K|3W|P|R]|$J|3X|K|3Y|P|R]|$J|3Z|K|40|P|R]]|9|@]|A|$]]|$1|1F|3|H|5|I|7|41|8|@]|9|@$J|42|K|43|1|44]]|A|$]]|$1|1G|3|1H|5|F|7|45|8|@$J|46|K|47|P|R]|$J|48|K|49|P|R]|$J|4A|K|4B|P|R]]|9|@]|A|$]]|$1|1I|3|1J|5|6|7|4C|8|@]|9|@]|A|$B|C]]|$1|1K|3|1L|5|F|7|4D|8|@]|9|@]|A|$]]|$1|1M|3|1N|5|6|7|4E|8|@]|9|@]|A|$B|C]]|$1|1O|3|1P|5|F|7|4F|8|@$J|4G|K|4H|P|R]]|9|@]|A|$]]|$1|1Q|3|1R|5|F|7|4I|8|@]|9|@$J|4J|K|4K|1|4L]]|A|$]]|$1|1S|3|-4|5|F|7|4M|8|@]|9|@]|A|$]]]|1T|$1U|$5|1V|1W|1X|A|$1Y|1Z|20|-4]]|21|$5|1V|1W|1X|A|$1Y|22|20|-4]]|23|$5|1V|1W|1X|A|$1Y|24|20|-4]]|25|$5|1V|1W|1X|A|$1Y|26|20|-4]]|27|$5|28|1W|29|A|$2A|2B]]]]

<pre class="lang-none prettyprint-override"><code>1. User touch
2. event is created
3. hit testing by coordinates - find first responder - UIView and successors (UIWindow) 
 3.1 hit testing - recursive find the most deep view
 3.1.1 point inside - check coordinates
4. Send Touch Event to the First Responder
</code></pre>
<h2 id="class-diagram">Class diagram</h2>
<img src="https://i.stack.imgur.com/LLKhr.png" height="450">
<h2 id="hit-testing">3 Hit Testing</h2>
Find a <code>First Responder</code>
<code>First Responder</code> in this case is the deepest <code>UIView</code> <code>point()</code>(<code>hitTest()</code> uses <code>point()</code> internally) method of which returned true. It always go through <code>UIApplication -&gt; UIWindow -&gt; First Responder</code>
<pre><code>func hitTest(_ point: CGPoint, with event: UIEvent?) -&gt; UIView?
func point(inside point: CGPoint, with event: UIEvent?) -&gt; Bool
</code></pre>
Internally <code>hitTest()</code> looks like
<pre><code>func hitTest() -&gt; View? {

 if (isUserInteractionEnabled == false || isHidden == true || alpha == 0 || point() == false) { return nil }

 for subview in subviews {
 if subview.hitTest() != nil {
 return subview
 }
 }
 
 return nil

}
</code></pre>
<h2 id="send-touch-event-to-the-first-responder">4 Send Touch Event to the <code>First Responder</code></h2>
<pre><code>//UIApplication.shared.sendEvent()

//UIApplication, UIWindow
func sendEvent(_ event: UIEvent)

//UIResponder
func touchesBegan(_ touches: Set&lt;UITouch&gt;, with event: UIEvent?)
func touchesMoved(_ touches: Set&lt;UITouch&gt;, with event: UIEvent?)
func touchesEnded(_ touches: Set&lt;UITouch&gt;, with event: UIEvent?)
func touchesCancelled(_ touches: Set&lt;UITouch&gt;, with event: UIEvent?)
</code></pre>
Let's take a look at example
<img src="https://i.stack.imgur.com/FvbjU.png" height="350"> <img src="https://i.stack.imgur.com/24jH5.jpg" height="350">
Responder Chain
It a kind of <code>chain of responsibility</code> pattern. It consists of <code>UIResponser</code> who can handle <code>UIEvent</code>. In this case it starts from first responder who overrides <code>touch...</code>. <code>super.touch...</code> calls next link in responder chain
<img src="https://i.stack.imgur.com/QN10u.png" width="700">
<code>Responder chain</code> is also used by <code>addTarget</code> or <code>sendAction</code> approaches like event bus
<pre><code>//UIApplication.shared.sendAction()
func sendAction(_ action: Selector, to target: Any?, from sender: Any?, for event: UIEvent?) -&gt; Bool
</code></pre>
Take a look at example
<pre><code>class AppDelegate: UIResponder, UIApplicationDelegate {
 @objc
 func foo() {
 //this method is called using Responder Chain
 print(&quot;foo&quot;) //foo
 }
}

class ViewController: UIViewController {
 func send() {
 UIApplication.shared.sendAction(#selector(AppDelegate.foo), to: nil, from: view1, for: nil)
 }
}
</code></pre>
*<code>isExclusiveTouch</code> is taken into account when handling multitouch
<a href="https://stackoverflow.com/a/57222691/4770877">[Android onTouch]</a>

While most apple documents are very well written, I think '<a href="http://developer.apple.com/library/ios/#DOCUMENTATION/EventHandling/Conceptual/EventHandlingiPhoneOS/Introduction/Introduction.html" rel="noreferrer">Event Handling Guide for iOS</a>' is an exception. It's hard for me to clearly understand what's been described there.

The document says, 

<blockquote>
 In hit-testing, a window calls <code>hitTest:withEvent:</code> on the top-most view of the view hierarchy; this method proceeds by recursively calling <code>pointInside:withEvent:</code> on each view in the view hierarchy that returns YES, proceeding down the hierarchy until it finds the subview within whose bounds the touch took place. That view becomes the hit-test view.
</blockquote>

So is it like that only <code>hitTest:withEvent:</code> of the top-most view is called by the system, which calls <code>pointInside:withEvent:</code> of all of subviews, and if the return from a specific subview is YES, then calls <code>pointInside:withEvent:</code> of that subview's subclasses?

Event handling for iOS - how hitTest:withEvent: and pointInside:withEvent: are related?

事件总线

Swift

虽然大多数苹果文档都写得很好，但我认为'‘是个例外。我很难清楚地理解这里所描述的内容。文件上说，在命中测试中，窗口在视图层次结构的最顶层视图上调用hitTest:withEvent:；此方法通过递归地对视图层次结构中返回YES的每个视图调用pointInside:withEvent:，沿着层次结构向下进行，直到找到发生...

问iOS的事件处理- hitTest:withEvent:和pointInside:withEvent:是如何相关的？
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问iOS的事件处理- hitTest:withEvent:和pointInside:withEvent:是如何相关的？
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