Find hostView or hostViewController

FindHost.swift

import UIKit


// MARK: - FindHostView

protocol FindHostView {
    associatedtype T
    var hostView: T? { get }
}

extension FindHostView where Self: UIView {
    var hostView: T? {
        var sv = superview
        while nil != sv {
            if let s = sv as? T  {
                return s
            }
            sv = sv?.superview
        }
        return nil
    }
}

// UICollectionViewCell 和 header/footer 都是ReusableView类型
extension UICollectionReusableView: FindHostView {
    typealias T = UICollectionView
}
extension UITableViewCell: FindHostView {
    typealias T = UITableView
}
extension UITableViewHeaderFooterView: FindHostView {
    typealias T = UITableView
}

// MARK: - FindHostViewController

protocol FindHostViewController {
    var hostViewController: UIViewController? { get }
}
extension UIView: FindHostViewController {
    var hostViewController: UIViewController? {
        var r = next
        while nil != r {
            if let vc = r as? UIViewController {
                return vc
            }
            r = r?.next
        }
        return nil
    }
}

// MARK: - forward performAction
// UITableViewDelegate 和 UICollectionViewDelegate 都有 performAction 方法，
// 此委托方法可用于将 cell / header / footer 上的事件转发到它的 delegate

extension UITableView {
    /// supplement for indexPath(for row: UITableViewCell)
    func indexPath(for headerFooter: UITableViewHeaderFooterView) -> IndexPath? {
        let rect = headerFooter.frame
        for i in 0..<numberOfSections {
            if rect == rectForHeader(inSection: i) {
                return IndexPath.init(row: -1, section: i) // 头部用-1
            } else if rect == rectForFooter(inSection: i) {
                return IndexPath.init(row: -2, section: i) // 底部用-2
            }
        }
        return nil
    }
}

extension FindHostView where Self: UICollectionViewCell {
    func forward(for aSelector: Selector) {
        if let cv = hostView, let ip = cv.indexPath(for: self) {
            cv.delegate?.collectionView?(cv, performAction: aSelector, forItemAt: ip, withSender: self)
        }
    }
}
extension FindHostView where Self: UITableViewCell {
    func forward(for aSelector: Selector) {
        if let cv = hostView, let ip = cv.indexPath(for: self) {
            cv.delegate?.tableView?(cv, performAction: aSelector, forRowAt: ip, withSender: self)
        }
    }
}
extension FindHostView where Self: UITableViewHeaderFooterView {
    func forward(for aSelector: Selector) {
        if let cv = hostView, let ip = cv.indexPath(for: self) {
            cv.delegate?.tableView?(cv, performAction: aSelector, forRowAt: ip, withSender: self)
        }
    }
}

//protocol ReusableViewInScrollView {
//    var reuseIdentifier: String? { get }
//    func prepareForReuse()
//}
//extension UICollectionReusableView: ReusableViewInScrollView {}
//extension UITableViewCell: ReusableViewInScrollView {}
//extension UITableViewHeaderFooterView: ReusableViewInScrollView {}