I want to move an asset from one album to another. But I could only find information on creating and deleting assets. The reason I want to move instead of creating a new one and deleting the old copy is, I want to preserve the bits of data like the localIdentifier of the asset. If I recreate an asset in another album, it will be assigned a new localIdentifier, am I right?
But it seems it's not possible. So I resorted to copying the asset at least. But it's giving me trouble as well.
Here's my code.
func copyAsset() {
if let assets = getAssetsFromCollection(collectionTitle: "Old") {
if getAssetColection("New") == nil {
createCollection("New") { collection in
if let collection = collection {
print("Collection created")
self.copyAssetsToCollection(assets, toCollection: collection)
}
}
}
}
}
/**
Copy assets to album.
- parameter assets: Array of assets to copy.
- parameter collection: The collection where the assets need to be copied.
*/
func copyAssetsToCollection(assets: [PHAsset], toCollection collection: PHAssetCollection) {
PHPhotoLibrary.sharedPhotoLibrary().performChanges({
let asset = assets.first!
print(asset.localIdentifier)
let assetChangeRequest = PHAssetChangeRequest(forAsset: asset)
let assetPlaceholder = assetChangeRequest.placeholderForCreatedAsset!
let collectionChangeRequest = PHAssetCollectionChangeRequest(forAssetCollection: collection)!
collectionChangeRequest.addAssets([assetPlaceholder])
}, completionHandler: { success, error in
if success {
print("Photo copied to collection")
} else {
if let error = error {
print("Error adding photos to collection: \(error.code) - \(error.localizedDescription)")
}
}
})
}
/**
Retrieve the album for the given title.
- parameter title: Album title.
- returns: Album if it exists. nil if it doesn't.
*/
func getAssetColection(title: String) -> PHAssetCollection? {
let fetchOptions = PHFetchOptions()
fetchOptions.predicate = NSPredicate(format: "title ==[cd] %@", title)
if let collection = PHAssetCollection.fetchAssetCollectionsWithType(.Album, subtype: .AlbumRegular, options: fetchOptions).firstObject {
return collection as? PHAssetCollection
}
return nil
}
/**
Get assets from a given album.
- parameter title: Album title.
- returns: An array of assets if they exist. nil if they don't.
*/
func getAssetsFromCollection(collectionTitle title: String) -> [PHAsset]? {
var assets = [PHAsset]()
if let collection = getAssetColection(title) {
let fetchOptions = PHFetchOptions()
fetchOptions.predicate = NSPredicate(format: "mediaType == %d", PHAssetMediaType.Image.rawValue)
let fetchResult = PHAsset.fetchAssetsInAssetCollection(collection, options: fetchOptions)
fetchResult.enumerateObjectsUsingBlock { object, index, stop in
if let asset = object as? PHAsset {
assets.append(asset)
}
}
return assets
}
return nil
}
/**
Create an album in Photos app.
- parameter title: Album title.
- parameter completion: Album if successfully created. nil if it fails.
*/
func createCollection(title: String, completion: (collection: PHAssetCollection?) -> ()) {
var albumPlaceholder: PHObjectPlaceholder!
PHPhotoLibrary.sharedPhotoLibrary().performChanges({
let request = PHAssetCollectionChangeRequest.creationRequestForAssetCollectionWithTitle(title)
albumPlaceholder = request.placeholderForCreatedAssetCollection
}, completionHandler: { success, error in
if success {
let fetchResult = PHAssetCollection.fetchAssetCollectionsWithLocalIdentifiers([albumPlaceholder.localIdentifier], options: nil)
completion(collection: fetchResult.firstObject as? PHAssetCollection)
} else {
if let error = error {
print("Failed to create album: \(title) in Photos app: \(error.code) - \(error.localizedDescription)")
completion(collection: nil)
}
}
})
}
The app crashes at the line let assetPlaceholder = assetChangeRequest.placeholderForCreatedAsset! for finding nil value for the placeholderForCreatedAsset. Which means PHAssetChangeRequest(forAsset: asset) can only be used to changing an asset's metadata and not duplicating it.
Is there any other way to do this? Any workaround or hack? I'll really appreciate any help.
