ViewController不启动

Question

我有问题。
当我选择cell UICollectionView时，我必须转到下一个ViewController，但它不起作用。
NavigationController推送ViewController，我的object已初始化，但我保持当前的控制器

出了什么问题？
为什么推送后的NavigationController不知道RoomViewController？它在ViewControllers列表中不存在：

StoryBoard截图：

初始ViewController，它推送MainViewController代码：

func showMainViewController(house: NLHouse) {
        let mainController = self.storyboard?.instantiateViewController(withIdentifier: "MainViewController") as? MainViewController
        if let mainController = mainController {
            mainController.house = house
            self.navigationController?.pushViewController(mainController, animated: true)
            print()
        }
    } 

MainViewController，它推送RoomViewController代码：

class MainViewController: UIViewController {

    @IBOutlet weak var devicesCollectionView: UICollectionView!
    var house: NLHouse?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print()
        devicesCollectionView.reloadData()
    }

}

extension MainViewController: UICollectionViewDelegate, UICollectionViewDataSource {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return house?.rooms?.count ?? 0
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let roomCell = devicesCollectionView.dequeueReusableCell(withReuseIdentifier: "roomCell", for: indexPath) as? RoomsCollectionViewCell
        if let roomCell = roomCell, let rooms = house?.rooms {
            roomCell.setRoomInfoInCell(room: rooms[indexPath.item])
        }
        return roomCell ?? UICollectionViewCell()
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if let roomController = self.storyboard?.instantiateViewController(withIdentifier: "RoomViewController") as? RoomViewController, let rooms = house?.rooms {
            roomController.room = rooms[indexPath.item]
            self.navigationController?.pushViewController(roomController, animated: true)
            print()
        }
    }
} 

推送代码：

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if let roomController = self.storyboard?.instantiateViewController(withIdentifier: "RoomViewController") as? RoomViewController, let rooms = house?.rooms {
            roomController.room = rooms[indexPath.item]
            self.navigationController?.pushViewController(roomController, animated: true)
            print()
        }  

推送类代码：

import UIKit

class RoomViewController: UIViewController {
    @IBOutlet weak var roomNameLabel: UILabel!
    @IBOutlet weak var devicesCollectionView: UICollectionView!
    var room: NLRoom?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewWillAppear(_ animated: Bool) {
        if let room = room {
            if let roomName = room.roomName {
                roomNameLabel.text = roomName
            }
            devicesCollectionView.reloadData()
        }
    }
}

extension RoomViewController: UICollectionViewDelegate, UICollectionViewDataSource {

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return room?.devices?.count ?? 0
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let deviceCell = devicesCollectionView.dequeueReusableCell(withReuseIdentifier: "deviceCell", for: indexPath) as? DevicesCollectionViewCell
        if let deviceCell = deviceCell, let devices = room?.devices {
            deviceCell.setDeviceInfoInCell(device: devices[indexPath.item])
        }
        return deviceCell ?? UICollectionViewCell()
    }
}

Answer 1

我在屏幕截图中看到的内容：您的viewController是导航控制器的root。另外两个视图控制器：main和room 告诉我，您如何展示MainViewController？ 我假设您将MainViewController从ViewController推送到创建新UINavigationController并将MainViewController设置为root viewController。然后，您尝试从RootViewController开始推送UINavigationController。 如果您希望项目正常工作 - 从storyboard中删除ViewController，请将MainViewController连接起来。这样，当您按RoomViewController时，它们将与您的MainViewController位于同一导航堆栈中 你需要你的结构看起来像这样：

将您的完整项目添加到zip文件中以进行调查。

<强>更新
在查看ViewController的suorce代码后，我发现正在从后台调用showMainViewController方法（从API接收数据后）。派遣主队列上的推送解决了问题 对于未来：你用UI做的任何事情都在主线程中进行。

Answer 2

请添加

super.viewWillAppear(animated) 

作为RoomViewController函数下面的第一行

    override func viewWillAppear(_ animated: Bool) 

您正在实例化控制器，但是当您按下viewWillAppear时，不会调用视图显示所需的已定义方法，因为未调用super.viewWillAppear。

或

您调用以下函数的控制器本身可能不在导航堆栈中。确保VC是导航控制器视图控制器的一部分，然后只有这将有效。

    self.navigationController?.pushViewController(roomController, animated: true)