如何在通过iOS swift photos framework保存照片时命名照片

我在swift中使用了

Xcode 6.3

（我认为是1.2版）。我的应用程序从web上的自定义服务器下载照片。然后，我希望它将具有给定文件名的照片保存到自定义相册中，该相册是通过照片框架创建的。我需要能够控制照片/文件名，因为我会跟踪我在数据库中下载的照片，然后需要按名称查看它们

我创建了一个自定义的PhotoAlbum类，试图将与相册交互的所有逻辑封装在其中。下载照片后，我可以调用以下代码，它可以创建相册并保存照片，但正如您在

savePhoto（）

方法中注意到的那样，我不知道在保存时在何处/如何使用photoName变量来命名照片。最后，我还需要知道如何在

loadPhoto（）

方法中按名称检索照片

谢谢你能给我的任何帮助/建议

let myAlbum = PhotoAlbum("MyAlbum") 

myAlbum.savePhoto(downloadedPhoto, 12)

class PhotoAlbum {

var albumName: String = ""
var albumExists: Bool = false
var assetCollection: PHAssetCollection!
var photosAsset: PHFetchResult!

init(albumName: String) {
    self.albumName = albumName
    self.initializeAlbum()
}

private func initializeAlbum() {

    let fetchOptions = PHFetchOptions()
    fetchOptions.predicate = NSPredicate(format: "title = %@", self.albumName)
    let collection: PHFetchResult = PHAssetCollection.fetchAssetCollectionsWithType(.Album, subtype: .Any, options: fetchOptions)

    if let firstObject: AnyObject = collection.firstObject {
        self.albumExists = true
        self.assetCollection = collection.firstObject as! PHAssetCollection
        if let ac = self.assetCollection {
            self.photosAsset = PHAsset.fetchAssetsInAssetCollection(self.assetCollection, options: nil)
        }
        println("\(self.albumName) album exists")
    }
    else {
        var albumPlaceHolder: PHObjectPlaceholder!

        PHPhotoLibrary.sharedPhotoLibrary().performChanges({

            let request = PHAssetCollectionChangeRequest.creationRequestForAssetCollectionWithTitle(self.albumName)
            albumPlaceHolder = request.placeholderForCreatedAssetCollection

        }, completionHandler: { (success: Bool, error: NSError!) in

            self.albumExists = success
            if success {
                let collection = PHAssetCollection.fetchAssetCollectionsWithLocalIdentifiers([albumPlaceHolder.localIdentifier], options: nil)
                self.assetCollection = collection.firstObject as! PHAssetCollection
                if let ac = self.assetCollection {
                    self.photosAsset = PHAsset.fetchAssetsInAssetCollection(self.assetCollection, options: nil)
                }
                println("\(self.albumName) album made")
            }
            else {
                println("Failed to create \(self.albumName) Album!!!!!!")
            }

        })
    }

}


func savePhoto(image: UIImage, photoID: Int) {
    let photoName = String(photoID)+".jpg"

    PHPhotoLibrary.sharedPhotoLibrary().performChanges({
        let assetRequest = PHAssetChangeRequest.creationRequestForAssetFromImage(image)
        let assetPlaceholder = assetRequest.placeholderForCreatedAsset
        let albumChangeRequest = PHAssetCollectionChangeRequest(forAssetCollection: self.assetCollection, assets: self.photosAsset)
        albumChangeRequest.addAssets([assetPlaceholder])
        }, completionHandler: { (success: Bool, error: NSError!) in

            print(success ? "image added" : "failed to add image")

    })
}

func loadPhoto(photoID: Int64) -> UIImage {
    let photoName = String(photoID)+".jpg"

    return UIImage(named: "no_photo")!
}

func renameAlbum(newAlbumName: String) {
    // need to create the new album and move all photos to that album then remove the old album

}

func reloadPhotos() {
    if let ac = self.assetCollection {
        self.photosAsset = PHAsset.fetchAssetsInAssetCollection(self.assetCollection, options: nil)
    }
}

---

您需要记录正在创建的资产的

localIdentifier

属性，而不是“命名”文件

localIdentifier

是一个持久标识符（即，在重启/重新加载期间，它将是资产的一致ID）

我已经拼凑了一些基本代码，您可以使用这些代码在保存图像时获取

localIdentifier

，并通过

localIdentifier

检索图像。希望这能让你走

import UIKit
import Photos

class MRPhotosHelper {

    var manager = PHImageManager.defaultManager()

    func saveImageAsAsset(image: UIImage, completion: (localIdentifier:String?) -> Void) {

        var imageIdentifier: String?

        PHPhotoLibrary.sharedPhotoLibrary().performChanges({ () -> Void in
            let changeRequest = PHAssetChangeRequest.creationRequestForAssetFromImage(image)
            let placeHolder = changeRequest.placeholderForCreatedAsset
            imageIdentifier = placeHolder.localIdentifier
        }, completionHandler: { (success, error) -> Void in
            if success {
                completion(localIdentifier: imageIdentifier)
            } else {
                completion(localIdentifier: nil)
            }
        })
    }

    func retrieveImageWithIdentifer(localIdentifier:String, completion: (image:UIImage?) -> Void) {
        let fetchOptions = PHFetchOptions()
        fetchOptions.predicate = NSPredicate(format: "mediaType == %d", PHAssetMediaType.Image.rawValue)
        let fetchResults = PHAsset.fetchAssetsWithLocalIdentifiers([localIdentifier], options: fetchOptions)

        if fetchResults.count > 0 {
            if let imageAsset = fetchResults.objectAtIndex(0) as? PHAsset {
                let requestOptions = PHImageRequestOptions()
                requestOptions.deliveryMode = .HighQualityFormat
                manager.requestImageForAsset(imageAsset, targetSize: PHImageManagerMaximumSize, contentMode: .AspectFill, options: requestOptions, resultHandler: { (image, info) -> Void in
                    completion(image: image)
                })
            } else {
                completion(image: nil)
            }
        } else {
            completion(image: nil)
        }
    }
}

然后，您可以这样做：

    // get a reference to our helper
    let helper = MRPhotosHelper()

    // a var to store the localIdentifier for the image we save
    var identifier:String?

    // save the image to library
    if let imageToSave = UIImage(named: "SomeImageName"){
        helper.saveImageAsAsset(imageToSave, completion: { (localIdentifier) -> Void in
            identifier = localIdentifier
        })
    }

    // other stuff

    // retrieve image from library at later date
    if let identifier = identifier {
        helper.retrieveImageWithIdentifer(identifier, completion: { (image) -> Void in
            let retrievedImage = image
        })
    }

---

在使用更新UI之前，您可能需要检查您是否回到完成闭包中的主线程。

此外，如果我无法“命名”照片，那么是否有任何类型的标识符绑定到该照片/资产，以便我可以保存，以便以后可以通过该标识符请求该照片？