PHAsset url返回nil图像

问题:加载带有从PHAsset获得的url的UIImage会返回nil。

请求PHAsset url的代码:

        let inputRequestOptions = PHContentEditingInputRequestOptions()
        inputRequestOptions.isNetworkAccessAllowed = true

        asset.requestContentEditingInput(with: inputRequestOptions, completionHandler: { (edittingInput, _) in
            guard let url = edittingInput?.fullSizeImageURL else {
                return
            }

            switch asset.mediaType {
            case .image: editMediaContentContainerPresenter.assets = [.image(url)]
            case .video: editMediaContentContainerPresenter.assets = [.movie(url)]
            default:
                debugPrint("unsupported asset")
            }
        })

将URL加载到我的UI组件内的UIImage的代码:

func image(for url: URL, maximumPixelSize: CGFloat) -> UIImage? {
    let options = [kCGImageSourceCreateThumbnailWithTransform: true,
                   kCGImageSourceCreateThumbnailFromImageAlways: true,
                   kCGImageSourceThumbnailMaxPixelSize: maximumPixelSize] as CFDictionary

    guard let source = CGImageSourceCreateWithURL(url as CFURL, nil) else {
        return nil
    }

    guard let imageReference = CGImageSourceCreateThumbnailAtIndex(source, 0, options) else {
        return nil
    }

    return UIImage(cgImage: imageReference, scale: UIScreen.main.scale, orientation: .up)
}

问题:如何获取有效的URL。

已考虑但需避免的解决方案:

2. 传递UIImage而不是URL