iOS将照片保存在特定应用专辑中

Question

我正在创建一个iOS 5应用程序.我想将照片保存到设备中.

我想将照片保存到我的应用程序专用的相册中,因此我需要创建相册,然后将照片保存到相册中.

我知道如何创建相册:

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library addAssetsGroupAlbumWithName:@"MY APP NAME" resultBlock:^(ALAssetsGroup *group) {
    //How to get the album URL?
} failureBlock:^(NSError *error) {
    //Handle the error
}];

我想现在为新专辑添加照片,我该怎么办？示例代码非常感谢!

Answer 1

您可以使用以下代码只更改相册的名称:

__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) {

}];

Answer 2

对于那些希望在iOS 9中执行此操作的人来说,事情变得有点复杂,因为不推荐使用ALAssetsLibrary以支持新的Photos库.

这里有一些Swift代码用于将UIImages添加到特定的专辑名称(如果不存在则创建专辑),您可能需要根据需要进行一些重构/优化:

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)
            }
        }
    )
}

Answer 3

对于那些寻找Eddy的答案的人 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);
        }
    }];
}