Вы можете сделать что-то вроде:
let foo = [1,undefined,3]
{ foo.map(e => !!e ? <Object /> : null )}
Эта статья , похоже, обеспечивает то, что вы ищете, с пользовательской категорией ALAssetsLibrary
. Похоже, есть некоторые полезные комментарии ниже статьи, которые также могут помочь в производительности.
https://github.com/amazingmanthere/ZCPhotoLibrary
Это простой класс утилиты для сохранения или удаления активов в библиотеке системных фотографий.
Для тех, кто хочет сделать это с iOS 9, ситуация немного усложнилась, поскольку ALAssetsLibrary устарела в пользу новой библиотеки фотографий.
Вот какой код Swift для добавления UIImages в (создание альбома, если оно не существует), вам может потребоваться сделать рефакторинг / оптимизацию для ваших нужд:
func insertImage(image : UIImage, intoAlbumNamed albumName : String) {
//Fetch a collection in the photos library that has the title "albumNmame"
let collection = fetchAssetCollectionWithAlbumName(albumName)
if collection == nil {
//If we were unable to find a collection named "albumName" we'll create it before inserting the image
PHPhotoLibrary.sharedPhotoLibrary().performChanges({
PHAssetCollectionChangeRequest.creationRequestForAssetCollectionWithTitle(albumName)
}, completionHandler: {(success : Bool, error : NSError?) in
if error != nil {
print("Error: " + error!.description)
}
if success {
//Fetch the newly created collection (which we *assume* exists here)
let newCollection = self.fetchAssetCollectionWithAlbumName(albumName)
self.insertImage(image, intoAssetCollection: newCollection!)
}
}
)
} else {
//If we found the existing AssetCollection with the title "albumName", insert into it
self.insertImage(image, intoAssetCollection: collection!)
}
}
func fetchAssetCollectionWithAlbumName(albumName : String) -> PHAssetCollection? {
//Provide the predicate to match the title of the album.
let fetchOption = PHFetchOptions()
fetchOption.predicate = NSPredicate(format: "title == '" + albumName + "'")
//Fetch the album using the fetch option
let fetchResult = PHAssetCollection.fetchAssetCollectionsWithType(
PHAssetCollectionType.Album,
subtype: PHAssetCollectionSubtype.AlbumRegular,
options: fetchOption)
//Assuming the album exists and no album shares it's name, it should be the only result fetched
let collection = fetchResult.firstObject as? PHAssetCollection
return collection
}
func insertImage(image : UIImage, intoAssetCollection collection : PHAssetCollection) {
//Changes for the Photos Library must be maded within the performChanges block
PHPhotoLibrary.sharedPhotoLibrary().performChanges({
//This will request a PHAsset be created for the UIImage
let creationRequest = PHAssetCreationRequest.creationRequestForAssetFromImage(image)
//Create a change request to insert the new PHAsset in the collection
let request = PHAssetCollectionChangeRequest(forAssetCollection: collection)
//Add the PHAsset placeholder into the creation request.
//The placeholder is used because the actual PHAsset hasn't been created yet
if request != nil && creationRequest.placeholderForCreatedAsset != nil {
request!.addAssets([creationRequest.placeholderForCreatedAsset!])
}
},
completionHandler: { (success : Bool, error : NSError?) in
if error != nil {
print("Error: " + error!.description)
}
}
)
}
Вы можете использовать следующий код, просто изменяя название альбома:
__weak ALAssetsLibrary *lib = self.library;
[self.library addAssetsGroupAlbumWithName:@"My Photo Album" resultBlock:^(ALAssetsGroup *group) {
///checks if group previously created
if(group == nil){
//enumerate albums
[lib enumerateGroupsWithTypes:ALAssetsGroupAlbum
usingBlock:^(ALAssetsGroup *g, BOOL *stop)
{
//if the album is equal to our album
if ([[g valueForProperty:ALAssetsGroupPropertyName] isEqualToString:@"My Photo Album"]) {
//save image
[lib writeImageDataToSavedPhotosAlbum:UIImagePNGRepresentation(image) metadata:nil
completionBlock:^(NSURL *assetURL, NSError *error) {
//then get the image asseturl
[lib assetForURL:assetURL
resultBlock:^(ALAsset *asset) {
//put it into our album
[g addAsset:asset];
} failureBlock:^(NSError *error) {
}];
}];
}
}failureBlock:^(NSError *error){
}];
}else{
// save image directly to library
[lib writeImageDataToSavedPhotosAlbum:UIImagePNGRepresentation(image) metadata:nil
completionBlock:^(NSURL *assetURL, NSError *error) {
[lib assetForURL:assetURL
resultBlock:^(ALAsset *asset) {
[group addAsset:asset];
} failureBlock:^(NSError *error) {
}];
}];
}
} failureBlock:^(NSError *error) {
}];
Для тех, кто ищет ответ Эдди в Objective-C.
#import <Photos/Photos.h>
- (void)insertImage:(UIImage *)image intoAlbumNamed:(NSString *)albumName {
//Fetch a collection in the photos library that has the title "albumNmame"
PHAssetCollection *collection = [self fetchAssetCollectionWithAlbumName: albumName];
if (collection == nil) {
//If we were unable to find a collection named "albumName" we'll create it before inserting the image
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
[PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle: albumName];
} completionHandler:^(BOOL success, NSError * _Nullable error) {
if (error != nil) {
NSLog(@"Error inserting image into album: %@", error.localizedDescription);
}
if (success) {
//Fetch the newly created collection (which we *assume* exists here)
PHAssetCollection *newCollection = [self fetchAssetCollectionWithAlbumName:albumName];
[self insertImage:image intoAssetCollection: newCollection];
}
}];
} else {
//If we found the existing AssetCollection with the title "albumName", insert into it
[self insertImage:image intoAssetCollection: collection];
}
}
- (PHAssetCollection *)fetchAssetCollectionWithAlbumName:(NSString *)albumName {
PHFetchOptions *fetchOptions = [PHFetchOptions new];
//Provide the predicate to match the title of the album.
fetchOptions.predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"title == '%@'", albumName]];
//Fetch the album using the fetch option
PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:fetchOptions];
//Assuming the album exists and no album shares it's name, it should be the only result fetched
return fetchResult.firstObject;
}
- (void)insertImage:(UIImage *)image intoAssetCollection:(PHAssetCollection *)collection {
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
//This will request a PHAsset be created for the UIImage
PHAssetCreationRequest *creationRequest = [PHAssetCreationRequest creationRequestForAssetFromImage:image];
//Create a change request to insert the new PHAsset in the collection
PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:collection];
//Add the PHAsset placeholder into the creation request.
//The placeholder is used because the actual PHAsset hasn't been created yet
if (request != nil && creationRequest.placeholderForCreatedAsset != nil) {
[request addAssets: @[creationRequest.placeholderForCreatedAsset]];
}
} completionHandler:^(BOOL success, NSError * _Nullable error) {
if (error != nil) {
NSLog(@"Error inserting image into asset collection: %@", error.localizedDescription);
}
}];
}