事件的传递和响应以及使用实例

在项目中使用响应链的地方

1. 在scrollView 中添加 slider

// - 方案一
-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{

    if (CGRectContainsPoint(self.subView.frame, point)) {
        self.scrollEnabled = NO;
        return YES;
    }
    self.scrollEnabled = YES;
    return YES;
}

// - 方案二
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    if (CGRectContainsPoint(self.subView.frame, point)) {
        self.scrollEnabled = NO;
        return [super hitTest:point withEvent:event];
    }
    self.scrollEnabled = YES;
    return [super hitTest:point withEvent:event];
}

// - 方案三
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
   UIView *view = [super hitTest:point withEvent:event];
   if([view isKindOfClass:[UISlider class]]) {
       self.scrollEnabled = NO;
   } else {
      self.scrollEnabled = YES;
   }
   return view;
}

2. 设置 scrollview 做的选项卡的 view 在第一个选项上是可以左滑返回

// - 设置 scrollview 做的选项卡的 view 在第一个选项上是可以左滑返回

-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{

    if ([[super hitTest:point withEvent:event] isKindOfClass:[UIControl class]]) {
        return [super hitTest:point withEvent:event];
    }else{
        if ((self.contentOffset.x == 0) && (point.x < 30)) {
            return nil;
        }
         return [super hitTest:point withEvent:event];
    }

}

3. 让事件穿透view

// - 设置事件可以穿透 view
@implementation DYContainerBgView
/** 可以透过事件 */
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    if ([super hitTest:point withEvent:event] == self) return nil;
    return [super hitTest:point withEvent:event];
}

@end

4. 事件传递的解析

1. 名词解释
   1. 事件传递 : 从上到下的顺序 （UIApplication–>UIWindow–>递归找到最合适处理的View），即从父控件到子控件的寻找过程 (事件传递最重要的就是找到合适的View来接收事件, 从父视图到子视图查找, 同一父视图, 从后加入到父视图 到 先加入到view的顺序遍历);
   2. 事件响应 : 从下到上的顺序 （实现View的touchesBegan方法，如果该View不能处理事件，则向上传递给它的父控件），从子控件传递给父控件(找到合适的View之后就会调用该View的touches方法进行响应处理具体的事件，如果当前的view 不响应touch 方法, 就查找上一响应者(superviwe, 或者view的控制器)来响应事件);

// - 示例代码 : 
- (void)viewDidLoad {
    [super viewDidLoad];
    
    QGView *v1 = [[QGView alloc]initWithFrame:CGRectMake(90, 90, 200, 200)];
    v1.backgroundColor = [UIColor redColor];
    v1.testStr = @"v1";
    [self.view addSubview:v1];
    
    QGView *v2 = [[QGView alloc]initWithFrame:CGRectMake(90, 90, 180, 180)];
    v2.backgroundColor = [UIColor greenColor];
    v2.testStr = @"v2";
    [self.view addSubview:v2];
    
    QGView *v3 = [[QGView alloc]initWithFrame:CGRectMake(90, 90, 160, 160)];
    v3.testStr = @"v3";
    v3.backgroundColor = [UIColor redColor];
    [self.view addSubview:v3];
    
    QGView *v31 = [[QGView alloc]initWithFrame:CGRectMake(0, 0, 120, 120)];
    v31.backgroundColor = [UIColor greenColor];
    v31.testStr = @"v31";
    [v3 addSubview:v31];
    
    QGView *v32 = [[QGView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
    v32.testStr = @"v32";
    v32.backgroundColor = [UIColor redColor];
    [v3 addSubview:v32];
    
    QGView *v33 = [[QGView alloc]initWithFrame:CGRectMake(0, 0, 80, 80)];
    v33.backgroundColor = [UIColor greenColor];
    v33.testStr = @"v33";
    [v3 addSubview:v33];
}

在self.view.subView 数组中, 后添加的view, 越在数组靠后的元素, 在view中的层级越高, 越接近用户

// - 测试 : 
1. 点击v3
2020-05-11 11:12:54.027766+0800 Demo_001[2008:56637] pointInside v3, ruturn : 1
2020-05-11 11:12:54.027995+0800 Demo_001[2008:56637] pointInside v33, ruturn : 0
2020-05-11 11:12:54.028168+0800 Demo_001[2008:56637] hitTest v33, ruturn : (null)
2020-05-11 11:12:54.028309+0800 Demo_001[2008:56637] pointInside v32, ruturn : 0
2020-05-11 11:12:54.028438+0800 Demo_001[2008:56637] hitTest v32, ruturn : (null)
2020-05-11 11:12:54.028569+0800 Demo_001[2008:56637] pointInside v31, ruturn : 0
2020-05-11 11:12:54.028674+0800 Demo_001[2008:56637] hitTest v31, ruturn : (null)
2020-05-11 11:12:54.029436+0800 Demo_001[2008:56637] hitTest v3, ruturn : <QGView: 0x7f9bede05ad0; frame = (90 90; 160 160); layer = <CALayer: 0x600003ec0780>>

2. 点击v33
2020-05-11 11:13:54.777979+0800 Demo_001[2008:56637] pointInside v3, ruturn : 1
2020-05-11 11:13:54.778181+0800 Demo_001[2008:56637] pointInside v33, ruturn : 1
2020-05-11 11:13:54.778399+0800 Demo_001[2008:56637] hitTest v33, ruturn : <QGView: 0x7f9bede0ca40; frame = (0 0; 80 80); layer = <CALayer: 0x600003ec0aa0>>
2020-05-11 11:13:54.778587+0800 Demo_001[2008:56637] hitTest v3, ruturn : <QGView: 0x7f9bede0ca40; frame = (0 0; 80 80); layer = <CALayer: 0x600003ec0aa0>>

3. 点击v31
2020-05-11 11:15:13.166848+0800 Demo_001[2008:56637] pointInside v3, ruturn : 1
2020-05-11 11:15:13.167039+0800 Demo_001[2008:56637] pointInside v33, ruturn : 0
2020-05-11 11:15:13.167145+0800 Demo_001[2008:56637] hitTest v33, ruturn : (null)
2020-05-11 11:15:13.167275+0800 Demo_001[2008:56637] pointInside v32, ruturn : 0
2020-05-11 11:15:13.167396+0800 Demo_001[2008:56637] hitTest v32, ruturn : (null)
2020-05-11 11:15:13.167503+0800 Demo_001[2008:56637] pointInside v31, ruturn : 1
2020-05-11 11:15:13.167669+0800 Demo_001[2008:56637] hitTest v31, ruturn : <QGView: 0x7f9bede08420; frame = (0 0; 120 120); layer = <CALayer: 0x600003ec0a40>>
2020-05-11 11:15:13.167813+0800 Demo_001[2008:56637] hitTest v3, ruturn : <QGView: 0x7f9bede08420; frame = (0 0; 120 120); layer = <CALayer: 0x600003ec0a40>>

4. 点击v1
2020-05-11 11:16:01.172527+0800 Demo_001[2008:56637] pointInside v3, ruturn : 0
2020-05-11 11:16:01.172711+0800 Demo_001[2008:56637] hitTest v3, ruturn : (null)
2020-05-11 11:16:01.172835+0800 Demo_001[2008:56637] pointInside v2, ruturn : 0
2020-05-11 11:16:01.172931+0800 Demo_001[2008:56637] hitTest v2, ruturn : (null)
2020-05-11 11:16:01.173068+0800 Demo_001[2008:56637] pointInside v1, ruturn : 1
2020-05-11 11:16:01.173249+0800 Demo_001[2008:56637] hitTest v1, ruturn : <QGView: 0x7f9bede06520; frame = (90 90; 200 200); layer = <CALayer: 0x600003ec01e0>>

结论 : 当前的vc的所有subView, 自外向内调用; 再从找到view的subView中, 自外向内调用