swift - "UICollectionView must be initialized with a non-nil layout parameter"但布局不为零

Question

我试图设置一个 UICollectionViewController，但我总是得到“UICollectionView 必须使用非零布局参数初始化”，尽管我确实初始化了布局并将其设置在 viewDidLoad 中。

这就是我所拥有的(刚刚创建了这个 VC):

class NotificationVC: UICollectionViewController{

let cellId = "notificationCell"
let layout = UICollectionViewFlowLayout()

override func viewDidLoad() {
    super.viewDidLoad()
    self.navigationController?.setNavBar()
    navigationItem.title = NSLocalizedString("notification.vc.title", comment: "Notification")
    navigationItem.rightBarButtonItem?.tintColor = UIColor.appWhite

    layout.scrollDirection = .vertical


    self.collectionView!.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
    collectionView.delegate = self
    collectionView.dataSource = self
    collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)

    // Do any additional setup after loading the view.
}
}

Answer 1

当您从另一个 View Controller 创建 NotificationVC 实例时，您应该使用 UICollectionViewFlowLayout 对象初始化该类。

如果您从另一个 View Controller 推送 NotificationVC，请像这样更改它

let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical
let notificationVC = NotificationVC(collectionViewLayout: layout)
self.navigationController?.pushViewController(notificationVC, animated: true)