項(xiàng)目中很多時(shí)候需要擴(kuò)大點(diǎn)擊（交互）區(qū)域，或子試圖超出了父視圖后，無法點(diǎn)擊或交互等，我們可以通過響應(yīng)者鏈
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event

show.jpg

-(void)setEnlargedMargin:(CGFloat)enlargedMargin{
    [self setEnlargeEdge:UIEdgeInsetsMake(enlargedMargin, enlargedMargin, enlargedMargin, enlargedMargin)];
}

-(void)setEnlargeEdge:(UIEdgeInsets)enlargeEdge{
    //拓展后的rect
    CGRect rect=CGRectMake(self.bounds.origin.x-enlargeEdge.left, self.bounds.origin.y-enlargeEdge.top, self.frame.size.width+enlargeEdge.left+enlargeEdge.right, self.frame.size.height+enlargeEdge.top+enlargeEdge.bottom);
    //存入
    objc_setAssociatedObject(self, &key_yjn_enlarged, @[NSStringFromCGRect(rect)], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    //掙脫父試圖束縛
    CGRect windowConvertRect = [self convertRect:self.bounds toView:[[[UIApplication sharedApplication] delegate] window]];
    [self freeView:self.superview rect:windowConvertRect enlargeEdge:enlargeEdge];
}

-(NSArray *)enlargedRect{
    NSArray *enlargedArr = objc_getAssociatedObject(self, &key_yjn_enlarged);
    if (enlargedArr) {
        return enlargedArr;
    }else{
        return @[NSStringFromCGRect(self.bounds)];
    }
}

2、掙脫父試圖束縛

#pragma mark - 掙脫父試圖束縛
-(void)freeView:(UIView *)superview rect:(CGRect)rect enlargeEdge:(UIEdgeInsets)enlargeEdge{
    if(superview == nil) return;
    
    //坐標(biāo)轉(zhuǎn)換
    UIWindow * window=[[[UIApplication sharedApplication] delegate] window];
    CGRect selfRect = [self convertRect:self.bounds toView:window];
    CGRect superViewRect = [superview convertRect:superview.bounds toView:window];
    
    if (CGRectContainsRect(superViewRect,selfRect)) {//完全包含
        return;
    }else{//不完全包含
        NSMutableArray *rectArr = [NSMutableArray arrayWithArray:[superview enlargedRect]];
        CGRect newRect = CGRectMake(rect.origin.x - superViewRect.origin.x, rect.origin.y - superViewRect.origin.y, rect.size.width, rect.size.height);
        
        CGRect newEnlargeRect = CGRectMake(newRect.origin.x-enlargeEdge.left, newRect.origin.y-enlargeEdge.top, newRect.size.width+enlargeEdge.left+enlargeEdge.right, newRect.size.height+enlargeEdge.top+enlargeEdge.bottom);
        
        [rectArr addObject:NSStringFromCGRect(newEnlargeRect)];
        objc_setAssociatedObject(superview, &key_yjn_enlarged, rectArr, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

        [self freeView:superview.superview rect:rect enlargeEdge:enlargeEdge];
    }
}

3、響應(yīng)者鏈傳遞

#pragma mark - 響應(yīng)者鏈
-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{
    for (NSString *edgeStr in [self enlargedRect]) {
        CGRect rect= CGRectFromString(edgeStr);
        if (CGRectContainsPoint(rect,point)) {
            return YES;
        }
    }
    return NO;
}

-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    // 1.判斷下窗口能否接收事件
    if (self.userInteractionEnabled == NO || self.hidden == YES ||  self.alpha <= 0.01){
        return nil;
    }
    // 2.判斷下點(diǎn)在不在窗口上
    // 不在窗口上
    if ([self pointInside:point withEvent:event] == NO){
        return nil;
    }

    // 3.從后往前遍歷子控件數(shù)組
    int count = (int)self.subviews.count;
    for (int i = count - 1; i >= 0; i--)     {
        // 獲取子控件
        UIView *childView = self.subviews[i];
        // 坐標(biāo)系的轉(zhuǎn)換,把窗口上的點(diǎn)轉(zhuǎn)換為子控件上的點(diǎn)
        // 把自己控件上的點(diǎn)轉(zhuǎn)換成子控件上的點(diǎn)
        CGPoint childP = [self convertPoint:point toView:childView];
        UIView *fitView = [childView hitTest:childP withEvent:event];
        if (fitView) {
            // 如果能找到最合適的view
            return fitView;
        }
    }
    // 4.沒有找到更合適的view，也就是沒有比自己更合適的view
    return self;
}

4、【注】如果要掙脫束縛，請想把view加到父view上，如[self.view addSubview:view];后才能添加enlargeEdge屬性，否則不生效。demo地址https://github.com/yinjining/hitEnlarged