项目中很多时候需要扩大点击（交互）区域，或子试图超出了父视图后，无法点击或交互等，我们可以通过响应者链
-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
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1、在category里添加属性
-(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);
//挣脱父试图束缚
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、挣脱父试图束缚
#pragma mark - 挣脱父试图束缚
-(void)freeView:(UIView *)superview rect:(CGRect)rect enlargeEdge:(UIEdgeInsets)enlargeEdge{
if(superview == nil) return;
//坐标转换
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、响应者链传递
#pragma mark - 响应者链
-(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.判断下窗口能否接收事件
if (self.userInteractionEnabled == NO || self.hidden == YES || self.alpha <= 0.01){
return nil;
}
// 2.判断下点在不在窗口上
// 不在窗口上
if ([self pointInside:point withEvent:event] == NO){
return nil;
}
// 3.从后往前遍历子控件数组
int count = (int)self.subviews.count;
for (int i = count - 1; i >= 0; i--) {
// 获取子控件
UIView *childView = self.subviews[i];
// 坐标系的转换,把窗口上的点转换为子控件上的点
// 把自己控件上的点转换成子控件上的点
CGPoint childP = [self convertPoint:point toView:childView];
UIView *fitView = [childView hitTest:childP withEvent:event];
if (fitView) {
// 如果能找到最合适的view
return fitView;
}
}
// 4.没有找到更合适的view，也就是没有比自己更合适的view
return self;
}
4、【注】如果要挣脱束缚，请想把view加到父view上，如[self.view addSubview:view];后才能添加enlargeEdge属性，否则不生效。demo地址https://github.com/yinjining/hitEnlarged
