paiai_ios/PaiAi/PaiaiUIKit/Reusable/UIKitDelegate/NavigationBarDelegate/NavigationBarProxy.swift

//
//  NavigationBarProxy.swift
//  PaiaiUIKit
//
//  Created by ffib on 2019/1/30.
//  Copyright © 2019 yb. All rights reserved.
//

import UIKit

class NavigationBarProxy: NSObject, UINavigationBarDelegate {
    weak var delegate: NavigationBarDelegate?

    init(target: NavigationBarDelegate) {
        delegate = target
    }
    
    func navigationBar(_ navigationBar: UINavigationBar, shouldPush item: UINavigationItem) -> Bool {
        guard let d = delegate else { return true }
        return d.navigationBar(navigationBar, shouldPush: item)
    }
}

extension UINavigationBar {
    private struct AssociatedKeys {
        static var proxyKey = "NavigationBarProxyKey"
    }
    
    private var proxy: NavigationBarProxy? {
        get { return objc_getAssociatedObject(self, &AssociatedKeys.proxyKey) as? NavigationBarProxy }
        set { objc_setAssociatedObject(self, &AssociatedKeys.proxyKey, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC) }
    }
    
    func setDelegate<T: NavigationBarDelegate>(_ target: T) {
        proxy = NavigationBarProxy(target: target)
        delegate = proxy
    }
}