Question

我正在尝试创建UICollectionView并且未在屏幕上加载。在我的应用程序委托中，我甚至将其设置为输入屏幕，它不会显示为黑屏。

class ChatRoom: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate, UICollectionViewDataSource, UICollectionViewDelegate {
    // Struct of Objects
    struct Object {
        var image: UIImage!
        var title: String!
    }

    // Properties
    var object: Object?
    var objects: [Object] = []
    var picker: UIImagePickerController!
    var ref: FIRDatabaseReference?

    @IBOutlet weak var collectionView2: UICollectionView!
    // Instance of a class
    var secondClass : ChatCell?

    // Do any additional setup after loading the view, typically from a nib.


    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // Firebase Data
        ref = FIRDatabase.database().reference()

        // CollectionView
        collectionView2?.delegate = self
        collectionView2?.dataSource = self
        collectionView2?.reloadData()

        // User Logged In
        checkIfUserLoggedIn()

        picker = UIImagePickerController()
        picker?.allowsEditing = false
        picker?.delegate = self
        picker?.sourceType = .photoLibrary
    }


    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! ChatCell
        let object = objects[indexPath.row]

        cell.chatLabel.text = object.title ?? ""
        cell.chatImage.image = object.image ?? UIImage()
        cell.layer.borderWidth = 2
        cell.layer.borderColor = UIColor.white.cgColor
        cell.layer.masksToBounds = true
        cell.layer.cornerRadius = 6

        return cell
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return objects.count  
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let itemWidth = collectionView2.bounds.width
        let itemHeight = collectionView2.bounds.height
        return CGSize(width: itemWidth, height: itemHeight)
    }

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
        switch info[UIImagePickerControllerOriginalImage] as? UIImage {
        case let .some(image):
            object?.image = image
        default:
            break
        }

        picker.dismiss(animated: true) {
            self.showCellTitleAlert()
        }
    }

    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        object = nil

        dismiss(animated: true) {
            self.collectionView2!.reloadData()
        }
    }

    // Alerts
    func showCellTitleAlert() {
        let alert = UIAlertController(title: "Cell Title", message: nil, preferredStyle: .alert)

        alert.addTextField { $0.placeholder = "Enter only 10 characters" }

        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel) { _ in
            self.object = nil
        })

        alert.addAction(UIAlertAction(title: "Save", style: .default) { _ in
            self.object?.title = (alert.textFields?.first.flatMap { $0.text })!
            self.object.flatMap { self.objects.append($0) }
            self.collectionView2?.reloadData()
        })

        present(alert, animated: true, completion: nil)
    }

    // Create new Cell
    @IBAction func didSelectCreateButton() {    
        object = Object()

        present(picker, animated: true, completion: nil)
    }

Answer 1

此处collectionView显示为空白，因为您没有填充objects dataSource的{{1}}数组。

UICollectionView未在屏幕上加载

1 个答案: