获取保存到照片库的图像的 PHAsset/localIdentifier

Question

我用来UIImageWriteToSavedPhotosAlbum将图像保存到照片应用程序。这是我发现的唯一可以让您执行此操作的功能。

这是我的代码：

import UIKit
import Photos

class ViewController: UIViewController {

    /// photo of a cactus
    let photoURL = URL(string: "https://raw.githubusercontent.com/aheze/DeveloperAssets/master/cactus.png")! /// in my app it's actually a local URL, but this also works
    
    func saveToPhotos() {
        DispatchQueue.global().async {
            let data = try? Data(contentsOf: self.photoURL)
            let image = UIImage(data: data!)
            UIImageWriteToSavedPhotosAlbum(image!, self, #selector(self.image(_:didFinishSavingWithError:contextInfo:)), nil)
        }
    }

    /// called when the image saving is complete
    @objc func image(_ image: UIImage, didFinishSavingWithError error: NSError?, contextInfo: UnsafeRawPointer) {
        print("Finished saving image")
        
        /// how to get localIdentifier of the image?
        let asset = PHAsset() /// obviously this does not work...
        let localIdentifier = asset.localIdentifier
    }
}

图像已成功保存到照片应用程序。但是，我需要保留对它的引用，最好是它的localIdentifier，这样我将来就可以在用户的​​其他照片中找到它。

例如，当我fetchAllPhotos稍后打电话时，我需要某种方法来找到我保存的仙人掌照片。

var allPhotos: PHFetchResult<PHAsset>?

func fetchAllPhotos() {
    let fetchOptions = PHFetchOptions() /// get all of user's photos
    allPhotos = PHAsset.fetchAssets(with: .image, options: fetchOptions)
    
    if let photos = allPhotos {
        photos.enumerateObjects { (asset, index, stop) in


            /// I need to find the image!  
            /// So I need to know its localIdentifier back when I saved it.
            if asset.localIdentifier == "cactus" {
                print("photo has been found")
            }
        }
    }
}

我有什么办法可以做到这一点吗？完成UIImageWriteToSavedPhotosAlbum处理程序引用，所以也许我可以从中UIImage创建一个？PHAsset或者也许我可以向 的UIImage元数据写入一些内容，我不确定。

Answer 1

尝试保存图像逻辑：

try PHPhotoLibrary.shared().performChangesAndWait {
    let imgReq = PHAssetChangeRequest.creationRequestForAsset(from: image)
    self.localID = imgReq.placeholderForCreatedAsset.localIdentifier
 }

您可以通过以下方式获取本地ID：

photos.enumerateObjects { (asset, index, stop) in
    if asset.localIdentifier == self.localID {
        print("photo was found")
    }
}