如何从照片的自定义相册，iOS SDK获取图像？

Question

我正在开发一款iOS应用，我需要像Instagram这样的画廊视图。我已经添加了图库视图，相机视图和视频视图，在拍摄图像后，它会保存到照片的自定义相册中。现在我想从自定义相册中检索这些图像并将其显示到Gallery的Collection视图。但是我却陷入了从自定义相册中检索这些图片的困境。任何帮助将不胜感激。

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

An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。

// CustomAlbum.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

// CustomAlbum.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

然后使用此方法获取图像按钮单击以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];
}

Answer 1

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

}];

Answer 2

尝试使用此代码。您可以使用以下代码在一个数组中获取所有图像： -

p.GetValue(this, null)

有关详细信息，请参阅Example app using Photos framework。

希望，这是你正在寻找的。任何关注都会回复给我。 ：）