I'm working on an iOS app in which I need gallery view like Instagram. I have added gallery View, camera View and video View, after taking image it saves to custom album of Photos. Now I want to retrieve those images from custom album and show it to Collection view of Gallery. But I'm getting stuck in retrieving those images from custom album. Any help will be appreciated.

编辑： 我添加了 PHPhotoLibrary 用于创建自定义相册，在此之前我添加了 AssetsLibrary 框架。

然后我创建了一个 NSObject 类（CustomAlbum），用于使用 PHPhotoLibrary 创建和管理自定义相册。

// 自定义相册.h

#import <Foundation/Foundation.h>
#import <Photos/Photos.h>


@interface CustomAlbum : NSObject

//Creating album with given name
+(void)makeAlbumWithTitle:(NSString *)title onSuccess:(void(^)(NSString *AlbumId))onSuccess onError: (void(^)(NSError * error)) onError;

//Get the album by name
+(PHAssetCollection *)getMyAlbumWithName:(NSString*)AlbumName;

//Add a image
+(void)addNewAssetWithImage:(UIImage *)image toAlbum:(PHAssetCollection *)album onSuccess:(void(^)(NSString *ImageId))onSuccess onError: (void(^)(NSError * error)) onError;

//get the image using identifier
+ (void)getImageWithIdentifier:(NSString*)imageId onSuccess:(void(^)(UIImage *image))onSuccess onError: (void(^)(NSError * error)) onError;


@end

// 自定义相册.m

#import "CustomAlbum.h"

@implementation CustomAlbum

#pragma mark - PHPhoto

+(void)makeAlbumWithTitle:(NSString *)title onSuccess:(void(^)(NSString *AlbumId))onSuccess onError: (void(^)(NSError * error)) onError
{
    //Check weather the album already exist or not
    if (![self getMyAlbumWithName:title]) {
        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            // Request editing the album.
            PHAssetCollectionChangeRequest *createAlbumRequest = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title];

            // Get a placeholder for the new asset and add it to the album editing request.
            PHObjectPlaceholder * placeHolder = [createAlbumRequest placeholderForCreatedAssetCollection];
            if (placeHolder) {
                onSuccess(placeHolder.localIdentifier);
            }

        } completionHandler:^(BOOL success, NSError *error) {
            NSLog(@"Finished adding asset. %@", (success ? @"Success" : error));
            if (error) {
                onError(error);
            }
        }];
    }
}

+(void)addNewAssetWithImage:(UIImage *)image toAlbum:(PHAssetCollection *)album onSuccess:(void(^)(NSString *ImageId))onSuccess onError: (void(^)(NSError * error)) onError
{
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        // Request creating an asset from the image.
        PHAssetChangeRequest *createAssetRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:image];

        // Request editing the album.
        PHAssetCollectionChangeRequest *albumChangeRequest = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:album];

        // Get a placeholder for the new asset and add it to the album editing request.
        PHObjectPlaceholder * placeHolder = [createAssetRequest placeholderForCreatedAsset];
        [albumChangeRequest addAssets:@[ placeHolder ]];

        NSLog(@"%@",placeHolder.localIdentifier);
        if (placeHolder) {
            onSuccess(placeHolder.localIdentifier);
        }

    } completionHandler:^(BOOL success, NSError *error) {
        NSLog(@"Finished adding asset. %@", (success ? @"Success" : error));
        if (error) {
            onError(error);
        }
    }];
}


+(PHAssetCollection *)getMyAlbumWithName:(NSString*)AlbumName
{
    #if 0
    NSString * identifier = [[NSUserDefaults standardUserDefaults]objectForKey:kAlbumIdentifier];
    if (!identifier) return nil;
    PHFetchResult *assetCollections = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[identifier]
                                                                                           options:nil];
    #else
    PHFetchResult *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum
                                                                               subtype:PHAssetCollectionSubtypeAlbumRegular
                                                                               options:nil];
    #endif
    NSLog(@"assetCollections.count = %lu", assetCollections.count);
    if (assetCollections.count == 0) return nil;

    __block PHAssetCollection * myAlbum;
    [assetCollections enumerateObjectsUsingBlock:^(PHAssetCollection *album, NSUInteger idx, BOOL *stop) {
        NSLog(@"album:%@", album);
        NSLog(@"album.localizedTitle:%@", album.localizedTitle);
        if ([album.localizedTitle isEqualToString:AlbumName]) {
            myAlbum = album;
            *stop = YES;
        }
    }];

    if (!myAlbum) return nil;
    return myAlbum;
}

+(NSArray *)getAssets:(PHFetchResult *)fetch
{
    __block NSMutableArray * assetArray = NSMutableArray.new;
    [fetch enumerateObjectsUsingBlock:^(PHAsset *asset, NSUInteger idx, BOOL *stop) {
        NSLog(@"asset:%@", asset);
        [assetArray addObject:asset];
    }];
    return assetArray;
}



+ (void)getImageWithIdentifier:(NSString*)imageId onSuccess:(void(^)(UIImage *image))onSuccess onError: (void(^)(NSError * error)) onError
{
    NSError *error = [[NSError alloc] init];
    PHFetchResult *assets = [PHAsset fetchAssetsWithLocalIdentifiers:@[imageId] options:nil];
    if (assets.count == 0) onError(error);

    NSArray * assetArray = [self getAssets:assets];
    PHImageManager *manager = [PHImageManager defaultManager];
    CGRect screenRect = [[UIScreen mainScreen] bounds];
    [manager requestImageForAsset:assetArray.firstObject targetSize:screenRect.size contentMode:PHImageContentModeAspectFit options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        onSuccess(result);
    }];
}

@end

然后使用此方法单击图像按钮来创建自定义相册并将图像保存在该自定义相册中。

 // Take Image Button Method

- (void)snapButtonPressed:(UIButton *)button
{
    [self.camera capture:^(LLSimpleCamera *camera, UIImage *image,
                           NSDictionary *metadata, NSError *error)
     {
         if(!error)
         {
             NSString * info = [NSString stringWithFormat:@"Size: %@  -  Orientation: %ld", NSStringFromCGSize(image.size), (long)image.imageOrientation];

             [CustomAlbum addNewAssetWithImage:image toAlbum:[CustomAlbum getMyAlbumWithName:CSAlbum] onSuccess:^(NSString *ImageId) {
                 NSLog(@"%@",ImageId);
                 recentImg = ImageId;
             } onError:^(NSError *error) {
                 NSLog(@"probelm in saving image");
             }];
         }
         else
         {
             NSLog(@"An error has occured: %@", error);
         }
     }
          exactSeenImage:YES];
}

这是有效的代码。

__block PHAssetCollection *collection;

// Find the album
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.predicate = [NSPredicate predicateWithFormat:@"title = %@", @"YOUR_CUSTOM_ALBUM_NAME"];
collection = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum
                                                  subtype:PHAssetCollectionSubtypeAny
                                                  options:fetchOptions].firstObject;

PHFetchResult *collectionResult = [PHAsset fetchAssetsInAssetCollection:collection options:nil];

[collectionResult enumerateObjectsUsingBlock:^(PHAsset *asset, NSUInteger idx, BOOL *stop) {


    //add assets to an array for later use in the uicollectionviewcell

}];