集合视图不会重新加载（Swift）

Question

我正在构建一个应用程序（快速）。其中一个选项应该是允许用户选择多张照片并上传它们，或者拍照并用它创建一个帖子。 我的想法基于以下层次结构：

按下新照片发布按钮 -> 用户会看到 UICollection 视图控制器，其中包含其库中的所有照片以及选择多张照片的选项（我正在重用一个单元格以使用照片库中的图像填充这些集合视图）上面应该是相机单元格（用户需要单击按钮以允许访问相机才能拍照）。这是来自模拟器的表示。

我已经编写了从库中获取照片并将它们添加到此处的数组中的代码（我将在下面展示这些代码）。 问题是当您首次加载应用程序并尝试发布时，系统会要求您授予对照片的访问权限。尽管用户有选择，（他们同意或不同意）他们的集合视图不会更新。

需要发生的事情 - 当用户被要求授予对照片的访问权限并且他们单击“确定”时，它应该在集合视图中重新加载数据，但事实并非如此。当他们点击“不允许”时，它应该关闭整个视图控制器。这是我的代码

class CVController: UICollectionViewController, UINavigationControllerDelegate, UICollectionViewDelegateFlowLayout {

var photosLibraryArray = [UIImage]()

override func viewDidLoad() {
    super.viewDidLoad()

    grabAllPhotosFromPhoneLibrary()

}

// Grab All Photos from Library
func grabAllPhotosFromPhoneLibrary () {

    let imageManager = PHImageManager.default()

    let requestOptions = PHImageRequestOptions()
    requestOptions.isSynchronous = true  // synchronous works better when grabbing all images
    requestOptions.deliveryMode = .opportunistic

    let fetchOptions = PHFetchOptions()
    fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)] // if false = last image we took would show first

    let fetchResult: PHFetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions)

    // 1. Are there photos in the library
    if fetchResult.count > 0 {

        // 2. if fetch.count > 0 it means there's at least 1 photo in the library
        for i in 0..<fetchResult.count {

            // 3. Cycling through the photos
            imageManager.requestImage(for: fetchResult.object(at: i), targetSize: CGSize(width: 200, height: 200), contentMode: .aspectFill, options: requestOptions, resultHandler:

                { image, error in
                    // 4. Append each image in the array
                    self.photosLibraryArray.append(image!)
            })
        }

    } else {
        print("You've got no photos")
        self.collectionView?.reloadData()
    }

我尝试在viewWillApear()、viewDidApear() 中调用collectionView.reloadData()，但没有任何效果。

Answer 1

    class CVController: UICollectionViewController, UINavigationControllerDelegate, UICollectionViewDelegateFlowLayout {

    var photosLibraryArray = [UIImage]()

    override func viewDidLoad() {
    super.viewDidLoad()

        checkPhotoLibraryPermission()
    }

---

添加下面提到的这个功能

    func checkPhotoLibraryPermission() {
        let status = PHPhotoLibrary.authorizationStatus()
        switch status {
        case .authorized: 
        //handle authorized status - // call this function here
                grabAllPhotosFromPhoneLibrary()
            case .denied, .restricted : 
                //handle denied status
            case .notDetermined: 
                // ask for permissions
                PHPhotoLibrary.requestAuthorization() { status in
                    switch status {
                    case .authorized: 
                        // call this function here
                        grabAllPhotosFromPhoneLibrary()

                    case .denied, .restricted: 
                        // as above
                        _ = navigationController?.popViewController(animated: true)
                    case .notDetermined: 
                        // won't happen but still, if you want to handle.
                }
        }
    }
    }

---

您可以相应地在以下功能中进行更改。根据需要。

    // Grab All Photos from Library
    func grabAllPhotosFromPhoneLibrary () {

    let imageManager = PHImageManager.default()

    let requestOptions = PHImageRequestOptions()
    requestOptions.isSynchronous = true  // synchronous works better when grabbing all images
    requestOptions.deliveryMode = .opportunistic

    let fetchOptions = PHFetchOptions()
    fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)] // if false = last image we took would show first

    let fetchResult: PHFetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions)

    // 1. Are there photos in the library
    if fetchResult.count > 0 {

        // 2. if fetch.count > 0 it means there's at least 1 photo in the library
        for i in 0..<fetchResult.count {

            // 3. Cycling through the photos
            imageManager.requestImage(for: fetchResult.object(at: i), targetSize: CGSize(width: 200, height: 200), contentMode: .aspectFill, options: requestOptions, resultHandler:

                { image, error in
                    // 4. Append each image in the array
                    self.photosLibraryArray.append(image!)
            })
        }
    //Use this reload data here as - you want the data loaded in the array first and then show the data.

    self.collectionView?.reloadData()

    } else {
        print("You've got no photos")
        //self.collectionView?.reloadData()

        // if you want to hide the view controller when there is no photo. pop the view controller from your navigation controller like this. 

     _ = navigationController?.popViewController(animated: true)
    }