MainNavigationProtocol.swift

MainNavigationProtocol.swift

import UIKit


protocol MainNavigationProtocol: class {
    var cached:Bool? {get set}
    static var storyboardName: String {get}
}

extension MainNavigationProtocol where Self : UIViewController {
    static var storyboardName: String {
        return "Main"
    }
    static func cached(from navVC: UINavigationController) -> Self {
        for vc in (navVC.viewControllers) {
            if vc.isKind(of: Self.self) {
                let controller = vc as! Self
                controller.cached = true
                return controller
            }
        }
        let vcId  = String(describing: self)
        var vc = instantiateController(fromStoryboard: storyboardName, withIdentifier: vcId) as? Self
        if  vc == nil {
            vc = Self()
        }
        vc!.cached = false
        return vc!
    }
    
    private static func instantiateController(fromStoryboard sbName: String, withIdentifier vcName: String) -> UIViewController? {
        let sb = UIStoryboard(name: sbName, bundle: nil)
        if let obj = sb.value(forKey: "identifierToNibNameMap") as? [String: Any],
               obj[vcName] != nil {
               return sb.instantiateViewController(withIdentifier: vcName)
        }
        return nil
    }
    
    func start(with navVC: UINavigationController?) {
        if let navVC = navVC {
            if let cached = cached, cached {
                navVC.popToViewController(self, animated: false)
            } else {
                navVC.pushViewController(self, animated: false)
            }
        }
    }
}