Swift纯代码页面传值

protocol BaseCtrlDelegate: class {
    func dismissPushedCtrl(controller: UIViewController)
}
//相同内容
class PushedCtrl: UIViewController {
    //相同内容

    weak var delegate: BaseCtrlDelegate!
}

protocol BaseCtrlDelegate {
    func dismissPushedCtrl(controller: UIViewController)
}

class BaseCtrl: UIViewController, BaseCtrlDelegate {
    var baseMsg: String! {
        didSet {
            print("BaseCtrl:" + baseMsg)
        }
    }
    //获取即将出栈的ViewController的实例，相当于获取它内部的数据（如msg）
    func dismissPushedCtrl(controller: UIViewController) {
        if let pushedCtrl = controller as? PushedCtrl{
            //传值
            baseMsg = pushCtrl.backMsg
            loginCtrl.navigationController?.popViewControllerAnimated(true)
        }
    }
   
    //......

    //跳转按钮点击事件
    func push() {
        baseMsg = "I'm coming!"
        let pushedCtrl = PushedCtrl()
        //传值
        pushedCtrl.backMsg = baseMsg
        pushedCtrl.delegate = self
        self.navigationController?.pushViewController(pushedCtrl, animated: true)
    }
}

class PushedCtrl: UIViewController {
     //......
    var backMsg: String! {
        didSet {
            print("PushedCtrl:" + backMsg)
        }
    }
    var delegate: BaseCtrlDelegate!
    //返回按钮点击事件
    func back() {
        backMsg = "I'm back!"
        delegate.dismissPushedCtrl(self)
    }
}