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我想將資源從一個相冊移到另一個相冊。但我只能找到有關創建和刪除資產的信息。我想移動而不是創建新副本並刪除舊副本的原因是，我想保留資產的各個位，如資產的localIdentifier。如果我在另一個相冊中重新創建資源，它將被分配一個新的localIdentifier，對嗎？將PHAsset從一個相冊移動/複製到另一個
但似乎這是不可能的。所以我採取至少複製資產。但它也給我帶來麻煩。
這是我的代碼。
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)
}
}
})
}
在尋找用於placeholderForCreatedAssetnil值線let assetPlaceholder = assetChangeRequest.placeholderForCreatedAsset!應用崩潰。這意味着PHAssetChangeRequest(forAsset: asset)只能用於更改資產的元數據，而不能複製它。
有沒有其他方法可以做到這一點？任何解決方法或破解？我會很感激任何幫助。