RequestContentEditingInput completionHandler不运行

Question

我有一个应用程序，我需要从手机中提取图像，并按照用户选择的顺序显示它们(我需要img按照所选的顺序，而不是“最近编辑的”，这就是为什么我不使用UIImagePickerController)

要做到这一点，我有一个页面，显示最新的50个图片，有可能加载更多。

下面的代码将显示图像路径和方向。

我的问题是: CompletionHandler (在RequestContentEditingInput中)只运行17次.我可以看到，每个图像都需要调用RequestContentEditingInput (在这个电话上是138次)

我试过等待，但什么也没发生。

当我有不到17张图片的时候，代码就会正常工作.

我试图在SemaphoreSlim代码中实现一个CompletionHandler锁，以控制我当时只处理10个图像，但最终的结果是完全没有处理相同的图像。

UpdateInfo:似乎所有的LivePhotos都没有被处理。

有人知道这里发生了什么吗？

一个解决办法的主意？

还有别的方法可以得到所有的图像路径和方向吗？

或者一个完全不同的解决方案，让用户从手机中提取图像，并获得用户选择的顺序？

    public class GalleryHelper : IGalleryHelper
    {
        private List<(string, string, string)> _retval;
        private nint _numberofImg = 0;
        private nint _currentImg = 0;

        public List<(string, string, string)> GetAllImgFromGallery()
        {
            _retval = new List<(string, string, string)>();
            _currentImg = 0;
            GetAllImg();
            return _retval;
        }

        private void GetAllImg()
        {
            var fetchOptions = new PHFetchOptions();

            PHFetchResult allPhotos = PHAsset.FetchAssets(PHAssetMediaType.Image, fetchOptions);
            _numberofImg = allPhotos.Count;

            Debug.WriteLine("Total img no + " + _numberofImg);

            for (nint i = 0; i < allPhotos.Count; i++)
            {
                Debug.WriteLine("Starting " + i);
                (allPhotos[i] as PHAsset).RequestContentEditingInput(new PHContentEditingInputRequestOptions(), CompletionHandler);
            }
        }

        private void CompletionHandler(PHContentEditingInput contentEditingInput, NSDictionary requestStatusInfo)
        {
            Debug.WriteLine("Starting CompletionHandler " + (1 + _currentImg));
            var path = contentEditingInput.FullSizeImageUrl.Path;
            if (path != null)
            {
                var orientation = contentEditingInput.FullSizeImageOrientation;

                switch (orientation)
                {
                    case CIImageOrientation.TopLeft:
                        //Standard position
                        _retval.Add((path, null, "0"));
                        break;

                    case CIImageOrientation.LeftBottom:
                        //Rotate 90 degrees clockwise
                        _retval.Add((path, null, "-90"));
                        break;

                    case CIImageOrientation.RightTop:
                        //Rotate 90 degrees counterclockwise
                        _retval.Add((path, null, "90"));
                        break;

                    case CIImageOrientation.BottomRight:
                        //Rotate 180 degrees
                        _retval.Add((path, null, "180"));
                        break;

                    case CIImageOrientation.BottomLeft:
                        //Mirror image rotated 180 degrees
                        _retval.Add((path, null, "180"));
                        break;

                    case CIImageOrientation.TopRight:
                        //Mirror image
                        _retval.Add((path, null, "0"));
                        break;

                    case CIImageOrientation.LeftTop:
                        //Mirror image rotate 90 degrees clockwise
                        _retval.Add((path, null, "-90"));
                        break;

                    case CIImageOrientation.RightBottom:
                        //Mirror image rotate 90 degrees counterclockwise.
                        _retval.Add((path, null, "90"));
                        break;

                    default:
                        _retval.Add((path, null, "0"));
                        break;
                }
            }
            _currentImg++;
            Debug.WriteLine("Images done " + _currentImg);
            MessagingCenter.Send((App)Xamarin.Forms.Application.Current, "ImagesReady", _retval);

        }
    }

运行时来自我的调试输出的粘贴：

[0:] Total img no + 138
[0:] Starting 0
[0:] Starting 1
(...)
[0:] Starting 137
[0:] Starting CompletionHandler 1
[0:] Images done 1
[0:] Starting CompletionHandler 2
[0:] Images done 2
[0:] Starting CompletionHandler 3
[0:] Images done 3
(...)
[0:] Starting CompletionHandler 15
[0:] Images done 15
[0:] Starting CompletionHandler 16
[0:] Images done 16
[0:] Starting CompletionHandler 17
[0:] Images done 17
Thread started: #17
Thread finished: #15
The thread 0xf has exited with code 0 (0x0).
Thread finished: #3

Answer 1

如果将来有人有同样的问题。使用PHImageManager.DefaultManager.RequestImageData()而不是PHAsset.RequestContentEditingInput()，因为如果您要求它处理大量图像，它不会崩溃。

我所做的事情是：

    var fetchOptions = new PHFetchOptions();
    PHFetchResult allPhotos = PHAsset.FetchAssets(PHAssetMediaType.Image, fetchOptions);
    _numberofImg = allPhotos.Count;
    Debug.WriteLine("Total img no + " + _numberofImg);
    await Task.Yield();
    await Task.Run(() => ImgProcess(allPhotos));
    return true;

private void ImgProcess(PHFetchResult allPhotos)
{
    //await Task.Run(() =>
    //{
        for (nint i = 0; i < allPhotos.Count; i++)
        {
            Debug.WriteLine("Starting " + i);
            var phasset = allPhotos[i] as PHAsset;
            var options = new PHImageRequestOptions()
            {
                Synchronous = true,
                NetworkAccessAllowed = false,
                DeliveryMode = PHImageRequestOptionsDeliveryMode.FastFormat
            };
            PHImageManager.DefaultManager.RequestImageData(phasset, options, ComplManager);
        }
    //});
    //return;
}

即使这个解决方案仍然有问题，当图像的数量超过300.