View事件响应穿透

//Only respond child view  
open class FallthroughView: UIView {  
    override open func point(inside point: CGPoint, with event: UIEvent?) -> Bool {  
        return subviews.map { [unowned self](v) -> Bool in  
            let new = v.convert(point, from: self)  
            return v.point(inside: new, with: event)  
            }.reduce(false) { $0 || $1 }  
    }  
}