swift - 如何从 UICollectionView 中选择多个图像并将它们传输到另一个 View Controller？

Question

代码是用 Swift 编写的。我正在构建一个社交应用程序，用户可以在其中发布帖子。我使用 Firebase 作为后端(数据库、存储)。因此，我有一个 UICollectionView，它从设备的照片库中获取所有照片，并使用自定义单元格填充 Collection View 。在同一个 View Controller 中，我有另一个自定义单元格，用户可以用它来拍照并用它来发帖。为了更清楚:

• 如果用户决定拍照，当他们点击“使用照片”时，他们需要被呈现给一个新的 View Controller ，该 View Controller 应该显示他们刚刚拍摄的照片以及其他选项(例如标题、使用 UITextFields 和 UITextView 的描述和标签)。

• 如果用户决定从他们自己的图库中选择多张照片，我必须以某种方式标记这些照片/单元格(即使用复选标记按钮)，将所选照片添加到数组中(有一些限制，也许 10 张照片顶部)。当他们单击“下一步”按钮时，需要将数组发送到新的 Post View Controller，其中所有图像都应该动态显示可能使用水平 UICollectionView(？!)(带有删除选项一张图片(如果它是意外选择的)，然后再一次，如上所述，有机会添加标题、描述等。现在，我不知道该怎么做。

我在寻找解决方案，但现在我已经坚持了几天，所以非常欢迎帮助!

这是我在 Collection View Controller 中的内容(PS:我没有包含从照片中获取图像的功能部分)

import UIKit
import Photos

class PrePhotoPostVC: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UINavigationControllerDelegate, UIImagePickerControllerDelegate, UICollectionViewDelegateFlowLayout {

@IBOutlet weak var nextButton: UIBarButtonItem!
var photosLibraryArray = [UIImage]()

@IBOutlet weak var collectionView: UICollectionView!

override func viewDidLoad() {
    super.viewDidLoad()

    checkPhotoLibraryPermission()
    setupCollectionViewDelegates()
}

@IBAction func cancelButtonPressed (_ sender: UIBarButtonItem) {
    dismiss(animated: true, completion: nil)
}

@IBAction func nextButtonPressed (_ sender: UIBarButtonItem) {
    nextButton.isEnabled = false
}

@IBAction func takeAphotoButtonPressed (_ sender: UIButton) {

    // Camera Autorization
    AVCaptureDevice.requestAccess(forMediaType: AVMediaTypeVideo) { response in
        if response {
            if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.camera) {
                let imagePicker = UIImagePickerController()
                imagePicker.delegate = self
                imagePicker.sourceType = UIImagePickerControllerSourceType.camera;
                imagePicker.allowsEditing = false
                self.present(imagePicker, animated: true, completion: nil)
            }
            else {
                print("Camera isn't available in similator")
            }
        }
        else {
            print("unautorized")
        }
    }
}

 func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 2
}
 func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    if section == 0 {
        return 1
    } else {
        return photosLibraryArray.count
    }
 }

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

    if indexPath.section == 0 {
        let cellCamera = collectionView.dequeueReusableCell(withReuseIdentifier: cellPrePostCameraCell, for: indexPath) 
        return cellCamera
    }
    else {
        let cellPhotoLibrary = collectionView.dequeueReusableCell(withReuseIdentifier: cellPrePostPhotoLibrary, for: indexPath) as! PrePhotoPostPhotoLIbraryCell
        cellPhotoLibrary.awakeFromNib()
        cellPhotoLibrary.photoLibraryImage.image = photosLibraryArray[indexPath.row]
        return cellPhotoLibrary
    }
}
}

此 UICollectionView 的屏幕截图:

这是我在图片库单元格中的代码:

import UIKit

class PrePhotoPostPhotoLIbraryCell: UICollectionViewCell {

    // MARK: Outlets
    @IBOutlet weak var photoLibraryImage: UIImageView!

    // var selectedPhotos = [UIImageView]()

    @IBAction func selectedButtonPressed(_ sender: UIButton) {
        self.layer.borderWidth = 3.0
        self.layer.borderColor = isSelected ? UIColor.blue.cgColor : UIColor.clear.cgColor
    }
    override func awakeFromNib() {

        photoLibraryImage.clipsToBounds = true
        photoLibraryImage.contentMode = .scaleAspectFill
        photoLibraryImage.layer.borderColor = UIColor.clear.cgColor
        photoLibraryImage.layer.borderWidth = 1
        photoLibraryImage.layer.cornerRadius = 5

    }
}

Answer 1

首先声明一个可变类型的数组，它将在其中存储选定的单元格项。

var _selectedCells : NSMutableArray = []

然后在您的 viewDidLoad 函数中添加以下代码。

 override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        //this will allow multiple selection on uicollectionviewcell
        CollectionView.allowsMultipleSelection=true //CollectionView is your CollectionView outlet
}

然后，实现collectionview的委托(delegate)函数来选择和取消选择单元格

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath){

        //add the selected cell contents to _selectedCells arr when cell is selected
        _selectedCells.add(indexPath)
        collectionView.reloadItems(at: [indexPath])
    }

    func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {

        //remove the selected cell contents from _selectedCells arr when cell is De-Selected

        _selectedCells.remove(indexPath)
        collectionView.reloadItems(at: [indexPath])
    }

我建议将所选项目的 NSIndexPath 保存在一个数组中，然后在委托(delegate)函数 cellForItemAt indexPath 中使用它作为比较的基础。

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

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "YOUR_CELL_Identifier", for: indexPath as IndexPath)

//add your tick mark image to the cell in your storyboard or xib file.
let tickImage = cell.viewWithTag(YOUR_IMAGE_TAG_HERE) as? UIImageView

//Show tickImage if the cell is selected and hide tickImage if cell is NotSelected/deSelected.or whatever action you want to perform in case of selection and deselection of cell.

if _selectedCells.contains(indexPath) {
cell.isSelected=true
collectionView.selectItem(at: indexPath, animated: true, scrollPosition: UICollectionViewScrollPosition.top)
tickImage?.isHidden=false
}
else{
cell.isSelected=false
tickImage?.isHidden=true
}
return cell
}

为了将项目发送到下一个 Controller ，从选定的索引路径中获取所有项目。