Question

对于学校我必须制作iOS应用程序。我想在其他视图中使用UICollectionView。我使用以下代码，但是当我使用self.libraryCollectionView.reloadData（）时，不会调用collectionView函数。名为libraryCollectionView的CollectionView应该包含一个Images库。在这里你可以看到我写的代码。

import UIKit

class CoverViewController: UIViewController, UICollectionViewDelegate, UINavigationControllerDelegate, UIImagePickerControllerDelegate, UICollectionViewDataSource  {

// MARK: Properties
@IBOutlet weak var photoImageView: UIImageView!
@IBOutlet weak var typeLabel: UILabel!
@IBOutlet weak var libraryCollectionView: UICollectionView!

var cover: Cover?
var images = [UIImage]()

override func viewDidLoad() {
    super.viewDidLoad()

    // Set up views if editing an existing Cover.
    if let cover = cover {
        photoImageView.image = cover.image
        typeLabel.text = cover.type
    }

    libraryCollectionView.delegate = self
    libraryCollectionView.dataSource = self

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

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


/*
// 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.
}
*/
@IBAction func addImage(_ sender: UIBarButtonItem) {
    let imagePicker = UIImagePickerController()
    imagePicker.delegate = self

    let alert = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet);

    alert.addAction(UIAlertAction(title: "Camera", style: .default, handler: { (action) in
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            imagePicker.sourceType = .camera
            self.present(imagePicker, animated: true, completion: nil)
        }
    }))

    alert.addAction(UIAlertAction(title: "Photo Library", style: .default, handler: { (action) in
        if UIImagePickerController.isSourceTypeAvailable(.photoLibrary) {
            imagePicker.sourceType = .photoLibrary
            self.present(imagePicker, animated: true, completion: nil)
        }
    }))

    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))

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

// Methods for ImagePicker
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
    if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
        images.append(pickedImage)
        DispatchQueue.main.async{
            self.libraryCollectionView.reloadData()
        }
    }

    dismiss(animated: true, completion: nil)
}

// Methods for CollectionView
func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 0
}

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

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cellIdentifier = "cell"
    let cell = libraryCollectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as! ImageCellView

    NSLog(String(images.count))

    cell.photoImageView.image = images[indexPath.row]

    return cell
}
}

Answer 1

numberOfSections(in collectionView: UICollectionView)应至少返回1。它的默认值也是1，因此您只需从代码中删除整个方法即可。

在其他视图中更新集合视图

1 个答案: