我正在尝试从youtube教程创建类似Facebook Messenger的应用程序。我有一个主页,用户单击BarButton打开聊天室。主页工作正常,直到我单击BarButton打开聊天,它会崩溃并显示以下错误消息“ UICollectionView必须使用非nil布局参数初始化”。我是iOS开发的新手,因此无法真正理解问题所在,因为我已经有了init方法。由于我有不同的看法,我是否在AppDelegate中缺少某些内容,这很令人困惑:(。非常感谢您的帮助。谢谢!
class ChatViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout { override func viewDidLoad() { super.viewDidLoad() navigationItem.title = "Chats" collectionView?.backgroundColor = UIColor.gray // Do any additional setup after loading the view. } override func viewWillAppear(_ animated: Bool) { collectionView?.register(ChatCell.self, forCellWithReuseIdentifier: "cellID") } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { return 3 } override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellID", for: indexPath) return cell } func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { return CGSize(width: view.frame.width, height: 100) } /* // MARK: - Navigation // In a storyboard-based application, you will often want to do a little preparation before navigation override func prepare(for segue: UIStoryboardSegue, sender: Any?) { // Get the new view controller using segue.destinationViewController. // Pass the selected object to the new view controller. } */ } class ChatCell: UICollectionViewCell { override init(frame: CGRect) { super.init(frame: frame) setupViews() } let profileImageView: UIImageView = { let imageView = UIImageView() imageView.contentMode = .scaleAspectFill imageView.translatesAutoresizingMaskIntoConstraints = false return imageView }() func setupViews() { addSubview(profileImageView) backgroundColor = UIColor.blue addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0" : profileImageView])) addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0" : profileImageView])) } required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") } }
可能当您显示ChatViewController时,您会看到类似以下内容:
让chatVC = ChatViewController()
但是根据 苹果文件:
UICollectionViewController类
在初始化控制器时,使用init(collectionViewLayout :)方法,可以指定集合视图应具有的布局。
因此,您需要:
let chatVC = ChatViewController(collectionViewLayout: UICollectionViewFlowLayout())