Swift:无法以编程方式推送查看 Controller

Question

我正在尝试使用此代码以编程方式推送到不同的 View Controller :

let loginVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginViewController") as! MenuController
self.navigationController?.pushViewController(loginVC, animated: true)

这是我的设置:我有一个名为 MenuController 的 swift 文件，其中包含此代码 我将标识符名称设置为:LoginViewController 我设置了两个 的类ViewControllers 设置为 MenuController。但每当我按下按钮触发事件时，它什么都不做。

这是我要求的其余代码:

import UIKit

class MenuController: UIViewController {

    var thingy = 0

    @IBAction func ThingyBttn(_ sender: UIButton) {
        if(thingy == 1) {
            print("ok")
        }else{
            print("good")

            let loginVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginViewController") as! MenuController
            self.navigationController?.pushViewController(loginVC, animated: true)
        }
    }

    @IBOutlet var myButton: UIButton!

    @IBAction func Button(_ sender: UIButton) {
        if let ButtonImage = myButton.image(for: .normal),
            let Image = UIImage(named: "ButtonAppuyer.png"),
            UIImagePNGRepresentation(ButtonImage) == UIImagePNGRepresentation(Image) {
            thingy = 1

            print("1")                
        } else {
            thingy = 2

            print("2")
        }   
    }

}

我知道代码的其他所有内容都可以正常工作，因为它正在打印消息。

Answer 1

您需要像这样从 navigationController 中插入您执行推送的 vc

self.navigationController?

是 nil ，或者以编程方式执行

编辑:

替换这个

let loginVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginViewController") as! MenuController
self.navigationController?.pushViewController(loginVC, animated: true)

与

let loginVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginViewController") as! MenuController
let nav = UINavigationController(rootViewController:self) 
(UIApplication.shared.delegate as! AppDelegate).window!.rootViewController = nav 
nav.pushViewController(loginVC, animated: true)