iOS Touch以及事件响应链（一）hit-testing

简介

本文的目的是让读者彻底了解，iOS系统是如何识别Touch事件，以及如何传递对应的事件到指定的View

iOS事件主要分为四种

1. touch事件
2. 运动事件
3. 远程事件
4. 按压事件
   参见UIEvent的type属性

typedef NS_ENUM(NSInteger, UIEventType) {
    UIEventTypeTouches,
    UIEventTypeMotion,
    UIEventTypeRemoteControl,
    UIEventTypePresses NS_ENUM_AVAILABLE_IOS(9_0),
};

1480993244519.png

这里只介绍第一种Touch事件

为了便于区分把TouchEvent的
touchesBegan:withEvent:叫做Touch,手势类型的叫Gesture.

TouchEvent.png

事件处理流程

1. App(DemoTSAplication类，UIApplication子类，代表当前应用)先通过hit-testing找到touch View.
2. 而后APP收到sendEvent:事件，传递给Window(TSWindow)的sendEvent:,由TSWindow分解成touchesBegan:withEvent：，touchesMoved:withEvent,touchesEnd:withEvent,touchesCancel:withEvent等事件。
3. 具体的手势识别以及Target-Action在TSWindow的sendEvent:收到Touch Event状态的UITouchPhaseBegan与UITouchPhaseEnded|UITouchPhaseCancelled之间进行。
   截屏2016_12_8_上午9_51.png

   当前controller叫hit-testing,controller对应的view叫AView,AView第一个子View叫BView,BView有一个唯一子ViewCView,AView第二个子View叫DView,DView没有子View。以此界面，来分析hit-testing

   点击AView

   时序图

   SequenceDiagram2.jpg

   时序图的步骤在一次touch调用了2遍，看日志，原因未知，没有查到资料。

   日志

   2016-12-08 11:00:07.546 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] Before
   2016-12-08 11:00:07.547 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] Before
   2016-12-08 11:00:07.547 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] After
   2016-12-08 11:00:07.547 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] Before
   2016-12-08 11:00:07.548 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] Before
   2016-12-08 11:00:07.548 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] After
   2016-12-08 11:00:07.548 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] Before
   2016-12-08 11:00:07.548 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] Before
   2016-12-08 11:00:07.549 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] After
   2016-12-08 11:00:07.549 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] After
   2016-12-08 11:00:07.549 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] Before
   2016-12-08 11:00:07.549 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] Before
   2016-12-08 11:00:07.550 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] After
   2016-12-08 11:00:07.550 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] After
   2016-12-08 11:00:07.550 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] After
   2016-12-08 11:00:07.551 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] After
   2016-12-08 11:00:07.551 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] Before
   2016-12-08 11:00:07.551 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] Before
   2016-12-08 11:00:07.551 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] After
   2016-12-08 11:00:07.552 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] Before
   2016-12-08 11:00:07.552 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] Before
   2016-12-08 11:00:07.552 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] After
   2016-12-08 11:00:07.552 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] Before
   2016-12-08 11:00:07.553 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] Before
   2016-12-08 11:00:07.553 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] After
   2016-12-08 11:00:07.553 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] After
   2016-12-08 11:00:07.553 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] Before
   2016-12-08 11:00:07.553 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] Before
   2016-12-08 11:00:07.554 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] After
   2016-12-08 11:00:07.554 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] After
   2016-12-08 11:00:07.554 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] After
   2016-12-08 11:00:07.554 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] After
   

   第一遍调试堆栈

   
   

   第二遍调试堆栈

   解析:

   1. 第一个收到hitTest:withEvent:肯定是TSWindow,TSWindow调用pointInside:withEvent:返回YES，代表点击在TSWindows上，倒序递归遍历TSWindowsubviews。
   2. 只有一个子ViewAView,调用AView的pointInside:withEvent:返回YES，倒序递归遍历AViewsubviews.
   3. 先遍历DView,调用DView的pointInside:withEvent:返回NO,DView的hitTest:withEvent:返回nil。
   4. 再遍历BView,,调用BView的pointInside:withEvent:返回NO,BView的hitTest:withEvent:返回nil。
   5. AView所有子View都返回nil了，就返回self.

   点击DView

   时序图

   SequenceDiagram3.jpg

   日志

   2016-12-08 14:30:34.886 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] Before
   2016-12-08 14:30:34.886 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] Before
   2016-12-08 14:30:34.886 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] After
   2016-12-08 14:30:34.887 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] Before
   2016-12-08 14:30:34.887 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] Before
   2016-12-08 14:30:34.888 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] After
   2016-12-08 14:30:34.888 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] Before
   2016-12-08 14:30:34.888 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] Before
   2016-12-08 14:30:34.888 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] After
   2016-12-08 14:30:34.889 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] After
   2016-12-08 14:30:34.889 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] After
   2016-12-08 14:30:34.889 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] After
   2016-12-08 14:30:34.890 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] Before
   2016-12-08 14:30:34.890 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] Before
   2016-12-08 14:30:34.890 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] After
   2016-12-08 14:30:34.890 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] Before
   2016-12-08 14:30:34.891 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] Before
   2016-12-08 14:30:34.891 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] After
   2016-12-08 14:30:34.891 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] Before
   2016-12-08 14:30:34.891 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] Before
   2016-12-08 14:30:34.892 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] After
   2016-12-08 14:30:34.892 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] After
   2016-12-08 14:30:34.892 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] After
   2016-12-08 14:30:34.892 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] After
   

   点击BView

   时序图

   SequenceDiagram4.jpg
   日志

   2016-12-08 15:19:16.611 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] Before
   2016-12-08 15:19:16.612 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] Before
   2016-12-08 15:19:16.612 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] After
   2016-12-08 15:19:16.613 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] Before
   2016-12-08 15:19:16.614 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] Before
   2016-12-08 15:19:16.614 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] After
   2016-12-08 15:19:16.615 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] Before
   2016-12-08 15:19:16.615 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] Before
   2016-12-08 15:19:16.616 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] After
   2016-12-08 15:19:16.616 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] After
   2016-12-08 15:19:16.617 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] Before
   2016-12-08 15:19:16.617 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] Before
   2016-12-08 15:19:16.617 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] After
   2016-12-08 15:19:16.618 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:CView] Before
   2016-12-08 15:19:16.618 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:CView] Before
   2016-12-08 15:19:16.619 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:CView] After
   2016-12-08 15:19:16.619 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:CView] After
   2016-12-08 15:19:16.620 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] After
   2016-12-08 15:19:16.620 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] After
   2016-12-08 15:19:16.621 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] After
   2016-12-08 15:19:16.621 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] Before
   2016-12-08 15:19:16.622 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] Before
   2016-12-08 15:19:16.622 TSEventDemo[35550:1352018] -[TSWindow pointInside:withEvent:] After
   2016-12-08 15:19:16.623 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] Before
   2016-12-08 15:19:16.623 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] Before
   2016-12-08 15:19:16.623 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:AView(MainView)] After
   2016-12-08 15:19:16.624 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] Before
   2016-12-08 15:19:16.624 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] Before
   2016-12-08 15:19:16.625 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:DView] After
   2016-12-08 15:19:16.625 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:DView] After
   2016-12-08 15:19:16.625 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] Before
   2016-12-08 15:19:16.625 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] Before
   2016-12-08 15:19:16.626 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:BView] After
   2016-12-08 15:19:16.626 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:CView] Before
   2016-12-08 15:19:16.626 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:CView] Before
   2016-12-08 15:19:16.627 TSEventDemo[35550:1352018] -[TSView pointInside:withEvent:] [name:CView] After
   2016-12-08 15:19:16.627 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:CView] After
   2016-12-08 15:19:16.628 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:BView] After
   2016-12-08 15:19:16.628 TSEventDemo[35550:1352018] -[TSView hitTest:withEvent:] [name:AView(MainView)] After
   2016-12-08 15:19:16.628 TSEventDemo[35550:1352018] -[TSWindow hitTest:withEvent:] After
   

   解析
   不再解析，总结成一句话：

   倒序递归subview,直到某个子ViewpointInside:withEvent:返回YES,没有subview或者subviews的hitTest:withEvent:返回nil,则返回self.

   点击CView

   用提供的Demo，自验看日志，即可。

   模拟代码

   发现用文字流程图对程序员来说，还没代码更直观。故附上模拟代码

   伪代码

   - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
   {
       if (self.hidden || !self.userInteractionEnabled || self.alpha < 0.01 || ![self pointInside:point withEvent:event] || ![self _isAnimatedUserInteractionEnabled]) {
           return nil;
       } else {
           for (UIView *subview in [self.subviews reverseObjectEnumerator]) {
               UIView *hitView = [subview hitTest:[subview convertPoint:point fromView:self] withEvent:event];
               if (hitView) {
                   return hitView;
               }
           }
           return self;
       }
   }
   

   Demo代码

   放在第二篇