集合视图无法重新加载（Swift）

Question

我正在构建一个应用程序（在swift中）。其中一个选项应该是允许用户选择多张照片并上传或拍照并使用它创建帖子。 我的想法基于以下层次结构：

按下新照片帖子按钮 - ＆gt;向用户呈现UICollection视图控制器，其中包含来自其库的所有照片以及用于选择多张照片的选项（我正在重复使用单元格用照片库中的图像填充这些集合视图）以及上面应该是相机单元格（用户需要点击按钮才能访问相机才能拍照。这是模拟器的表示。

我编写了从库中获取照片的代码，并将它们添加到数组中（我将在下面显示这些代码）。 问题是，当您第一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。

需要发生什么 - 当要求用户授予对照片的访问权限并单击“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View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collectionView.reloadData()，viewWillApear()中调用viewDidApear()，没有任何效果。

Answer 1

    class CVController: UICollectionViewController, UINavigationControllerDelegate, UICollectionViewDelegateFlowLayout {

    var photosLibraryArray = [UIImage]()

    override func viewDidLoad() {
    super.viewDidLoad()

        checkPhotoLibraryPermission()
    }

添加以下提到的功能

    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.
                }
        }
    }
    }

您可以相应地在下面的功能中进行更改。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)
    }