斯威夫特3 - 的CollectionView数据源没有返回

Question

我使用这段代码的有效细胞：https://www.youtube.com/watch?v=bNtsekO51iQ，但是当我实现我的数据，并使用collectionView.reloadData（）它与错误代码崩溃*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'the collection view's data source did not return a valid cell from -collectionView:cellForItemAtIndexPath: for index path <NSIndexPath: 0xc000000000000016> {length = 2, path = 0 - 0}'

class ChatLogController: UICollectionViewController, UICollectionViewDelegateFlowLayout { 

    var userId:Int? 
    var position:Int = 0 
    var otherAvatar:UIImage = UIImage(named: "defaultAvatar")! 
    var otherName:String = "" 
    var otherSex:String = "" 
    var otherBanned:Int = 0 
    var otherBlocked:Int = 0 
    var messagesDates:[String] = [] 
    var messagesText:[String] = [] 
    var messagesIds:[String] = [] 
    var messagesPics:[UIImage?] = [] 
    var messagesSeen:[Int] = [] 
    var messagesWhoSendIt:[Int] = [] 
    private let cellId = "cellId" 
    override func viewDidLoad() { 
     super.viewDidLoad() 
     collectionView?.register(ChatLogMessageCell.self, forCellWithReuseIdentifier: cellId) 
     collectionView!.isPrefetchingEnabled = false 
     loadChatsFor(position: position) 
    } override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { 
     return messagesIds.count 
    } 

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell { 
     let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath as IndexPath) as! ChatLogMessageCell 

     cell.messageTextView.text = messagesText[indexPath.row] 


      cell.profileImageView.image = UIImage(named: "defaultAvatar")! 

      let size = CGSize(width:250,height:1000) 
      let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin) 
      let estimatedFrame = NSString(string: messagesText[indexPath.row]).boundingRect(with: size, options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 18)], context: nil) 

     cell.messageTextView.frame = CGRect(x:48 + 8, y:0, width:estimatedFrame.width + 16, height:estimatedFrame.height + 20) 

     cell.textBubbleView.frame = CGRect(x:48, y:0, width:estimatedFrame.width + 16 + 8, height:estimatedFrame.height + 20) 

     return cell 
    } 

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { 
      let size = CGSize(width:250,height:1000) 
      let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin) 
      let estimatedFrame = NSString(string: messagesText[indexPath.row]).boundingRect(with: size, options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 18)], context: nil) 

     return CGSize(width:view.frame.width, height:estimatedFrame.height + 20) 
    } 


    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets { 
     return UIEdgeInsetsMake(8, 0, 0, 0) 
    } 

} 

class ChatLogMessageCell: BaseCell { 

    let messageTextView: UITextView = { 
     let textView = UITextView() 
     textView.font = UIFont.systemFont(ofSize: 18) 
     textView.text = "Sample message" 
     textView.backgroundColor = UIColor.clear 
     return textView 
    }() 

    let textBubbleView: UIView = { 
     let view = UIView() 
     view.backgroundColor = UIColor(white: 0.95, alpha: 1) 
     view.layer.cornerRadius = 15 
     view.layer.masksToBounds = true 
     return view 
    }() 

    let profileImageView: UIImageView = { 
     let imageView = UIImageView() 
     imageView.contentMode = .scaleAspectFill 
     imageView.layer.cornerRadius = 15 
     imageView.layer.masksToBounds = true 
     return imageView 
    }() 

    override func setupViews() { 
     super.setupViews() 

     addSubview(textBubbleView) 
     addSubview(messageTextView) 

     addSubview(profileImageView) 
     addConstraintsWithFormat(format:"H:|-8-[v0(30)]", views: profileImageView) 
     addConstraintsWithFormat(format:"V:[v0(30)]|", views: profileImageView) 
     profileImageView.backgroundColor = UIColor.red 
    } 

} 
extension UIView { 

    func addConstraintsWithFormat(format: String, views: UIView...) { 

     var viewsDictionary = [String: UIView]() 
     for (index, view) in views.enumerated() { 
      let key = "v\(index)" 
      viewsDictionary[key] = view 
      view.translatesAutoresizingMaskIntoConstraints = false 
     } 

     addConstraints(NSLayoutConstraint.constraints(withVisualFormat: format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary)) 
    } 


} 
class BaseCell: UICollectionViewCell { 
    override init(frame: CGRect) { 
     super.init(frame: frame) 
     setupViews() 
    } 

    required init?(coder aDecoder: NSCoder) { 
     fatalError("init(coder:) has not been implemented") 
    } 

    func setupViews() { 
    } 
} 

在loadChatsFor我从网络的阵列中的数据，我用collectionView.reloadData（），但是当执行此功能时它崩溃我的应用程序。我寻找答案，但没有成功。我已经添加IOS 10函数collectionView！.isPrefetchingEnabled = false在这个答案UICollectionView exception in UICollectionViewLayoutAttributes from iOS7加载，但也无法正常工作。甚至在reloadData之前和reloadData之后的方法collectionViewLayout invalidateLayout不会停止崩溃。那么我还能做些什么才能使它工作？

我在这个CollectionViewController未来从UITableViewCell的

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { 
    let layout = UICollectionViewFlowLayout() 
    let controller = ChatLogController(collectionViewLayout: layout) 
    controller.userId = chatUserIds[indexPath.row] 
    navigationController?.pushViewController(controller, animated: true) 
} 

我在班上的tableview

Answer 1

您还没有实施的UICollectionViewDataSource正确cellForItemAt方法的补充UICollectionViewDelegateFlowLayout。像这样在Swift 3中更改此方法的签名。

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { 

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath as IndexPath) as! ChatLogMessageCell 

    cell.messageTextView.text = messagesText[indexPath.row] 


    cell.profileImageView.image = UIImage(named: "defaultAvatar")! 

    let size = CGSize(width:250,height:1000) 
    let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin) 
    let estimatedFrame = NSString(string: messagesText[indexPath.row]).boundingRect(with: size, options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 18)], context: nil) 

    cell.messageTextView.frame = CGRect(x:48 + 8, y:0, width:estimatedFrame.width + 16, height:estimatedFrame.height + 20) 

    cell.textBubbleView.frame = CGRect(x:48, y:0, width:estimatedFrame.width + 16 + 8, height:estimatedFrame.height + 20) 

    return cell 
}