How to name a photo when saving via iOS swift photos framework

Question

I am using Xcode 6.3 with swift (I think version 1.2). My app downloads photos from a custom server on the web. Then I want it to save the photo with a given file name to the custom photo album, which was has created via the Photos Framework. I need to be able to control the photo/filename because I keep track of which photos I have downloaded in a database and later need to view them by name.

I created a custom PhotoAlbum class that I am trying to wrap all of the logic for interacting with the photo albums in. Once I download a photo I can call the following code and it works as far as creating the album and saving the photo, but as you will notice in the savePhoto() method I don't know where/how to use the photoName variable to name the photo when saving. Eventually, I will also need to know how to retrieve the photo by name as well in the loadPhoto() method.

Thanks for any help/advice you can give me.

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)
    }
}

Answer 1

Rather than 'naming' a file, you need to be taking a note of the localIdentifier property of the asset you are creating. localIdentifier is a persistent identifier (ie. it will be a consistent ID for the asset across restarts/reloads).

I've cobbled together some basic code that you could use to get the localIdentifier when saving an image, and retrieve and image by a localIdentifier. Hopefully this will get you going.

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)
        }
    }
}

You could then do something like this:

    // 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
        })
    }

You may want to check that you are back on the main thread in the completion closures before using to update the UI.