IOS 14 请求限制照片访问

如何解决IOS 14 请求限制照片访问

我正在尝试使用 PHPickerController 并访问 PHAsset 来获取文件名和文件大小，但 PHAsset 为空

var config = new PHPickerConfiguration(PHPhotoLibrary.SharedPhotoLibrary) {
    Filter = PHPickerFilter.ImagesFilter,SelectionLimit = 1
};
var picker= new PHPickerViewController(config) {
    ModalPresentationStyle = UIModalPresentationStyle.Popover,Delegate = new ImagePickerDelegate((fileSize,fileName,url) => {

    })
};

ViewController.PresentViewController(picker,true,null);

public class ImagePickerDelegate : PHPickerViewControllerDelegate
{
    public ImagePickerDelegate(Action<int,string,string> action)
    {
        Action = action;
    }

    public Action<int,string> Action { get; }

    public override void DidFinishPicking(PHPickerViewController picker,PHPickerResult[] results)
    {
        picker.dismissViewController(true,null);

        foreach (var result in results)
        {
            var asset = PHAsset.FetchAssets(result.AssetIdentifier,null)?.firstObject as PHAsset;
            // The asset are null
            var fileSize = asset.ValueForKey((Nsstring)"fileSize");
        }
    }
}

正如您在图片中看到的，请求对话框显示和代码不会在下一行暂停

var asset = PHAsset.FetchAssets(result.AssetIdentifier,null)?.firstObject as PHAsset;

并返回空

解决方法

您可以使用 FetchAssetsUsingLocalIdentifiers 方法获取 PHAsset 对象，然后它会返回值。

示例代码如下：

public override void DidFinishPicking(PHPickerViewController picker,PHPickerResult[] results)
{
    picker.DismissViewController(true,null);

    foreach (var result in results)
    {
       var refID = result.AssetIdentifier;
       string[] refIDs = new string[] { refID };
       var asset = PHAsset.FetchAssetsUsingLocalIdentifiers(refIDs,null)?.firstObject as PHAsset;
       
       // var fileSize = asset.ValueForKey((NSString)"fileSize");
    }
}

也可以看看这个native code link。