iOS 8 Photos 框架：使用 iOS8 获取所有相册的列表

Question

如何在 iOS8 中获取所有收藏的列表，包括相机胶卷（现在称为时刻）？

在 iOS 7 中，我使用 ALAssetGroup 枚举块，但这不包括 iOS 时刻，这似乎相当于 iOS7 中的相机胶卷。

    void (^assetGroupEnumerator)(ALAssetsGroup *, BOOL *) = ^(ALAssetsGroup *group, BOOL *stop)
    {
        if (group == nil) {// We're done enumerating
            return;
        }

        [group setAssetsFilter:[ALAssetsFilter allAssets]];
        if ([[sGroupPropertyName lowercaseString] isEqualToString:@"camera roll"] && nType == ALAssetsGroupSavedPhotos) {
            [_assetGroups insertObject:group atIndex:0];
        } else {
            [_assetGroups addObject:group];
        }
    };

    // Group Enumerator Failure Block
    void (^assetGroupEnumberatorFailure)(NSError *) = ^(NSError *error) {
        SMELog(@"Enumeration occured %@", [error description]);
    };

    // Enumerate Albums
    [_library enumerateGroupsWithTypes:kSupportedALAlbumsMask
                            usingBlock:assetGroupEnumerator
                          failureBlock:assetGroupEnumberatorFailure];
    }];

Answer 1

使用 Photos Framework 有点不同，但你可以达到相同的结果，你只需要部分地做。

1) 获取所有照片（iOS8 中的 Moments 或之前的相机胶卷）

PHFetchResult *allPhotosResult = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:nil];

如果您希望它们按创建日期排序，您只需添加PHFetchOptions，如下所示：

PHFetchOptions *allPhotosOptions = [PHFetchOptions new];
allPhotosOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];

PHFetchResult *allPhotosResult = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:allPhotosOptions];

现在，如果您愿意，您可以从 PHFetchResult 对象获取资产：

[allPhotosResult enumerateObjectsUsingBlock:^(PHAsset *asset, NSUInteger idx, BOOL *stop) {
    NSLog(@"asset %@", asset);
}];

2) 获取所有用户相册（通过附加排序，例如仅显示包含至少一张照片的相册）

PHFetchOptions *userAlbumsOptions = [PHFetchOptions new];
userAlbumsOptions.predicate = [NSPredicate predicateWithFormat:@"estimatedAssetCount > 0"];

PHFetchResult *userAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:userAlbumsOptions];

[userAlbums enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
        NSLog(@"album title %@", collection.localizedTitle);
}];

对于从PHFetchResult *userAlbums 返回的每个PHAssetCollection，您可以像这样获取PHAssets（您甚至可以将结果限制为仅包含照片资产）：

PHFetchOptions *onlyImagesOptions = [PHFetchOptions new];
onlyImagesOptions.predicate = [NSPredicate predicateWithFormat:@"mediaType = %i", PHAssetMediaTypeImage];
PHFetchResult *result = [PHAsset fetchAssetsInAssetCollection:collection options:onlyImagesOptions];

3) 获取智能相册

PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[smartAlbums enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
        NSLog(@"album title %@", collection.localizedTitle);
}];

使用智能相册需要注意的一点是，如果无法确定estimateAssetCount，collection.estimatedAssetCount 可以返回NSNotFound。正如标题所示，这是估计的。如果您想确定资产的数量，您必须执行 fetch 并获得如下计数：

PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];

资产数量 = assetsFetchResult.count

Apple 有一个示例项目可以满足您的需求：

https://developer.apple.com/library/content/samplecode/UsingPhotosFramework/ExampleappusingPhotosframework.zip（您必须是注册开发者才能访问）

Answer 2

这只是将@Ladislav 出色的公认答案翻译成 Swift：

// *** 1 ***
// Get all photos (Moments in iOS8, or Camera Roll before)
// Optionally if you want them ordered as by creation date, you just add PHFetchOptions like so:
let allPhotosOptions = PHFetchOptions()
allPhotosOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]

let allPhotosResult = PHAsset.fetchAssetsWithMediaType(PHAssetMediaType.Image, options: allPhotosOptions)

// Now if you want you can get assets from the PHFetchResult object:
allPhotosResult.enumerateObjectsUsingBlock({ print("Asset \($0.0)") })

// *** 2 ***
// Get all user albums (with additional sort for example to only show albums with at least one photo)
let userAlbumsOptions = PHFetchOptions()
userAlbumsOptions.predicate = NSPredicate(format: "estimatedAssetCount > 0")

let userAlbums = PHAssetCollection.fetchAssetCollectionsWithType(PHAssetCollectionType.Album, subtype: PHAssetCollectionSubtype.Any, options: userAlbumsOptions)

userAlbums.enumerateObjectsUsingBlock({
    if let collection = $0.0 as? PHAssetCollection {
        print("album title: \(collection.localizedTitle)")
        //For each PHAssetCollection that is returned from userAlbums: PHFetchResult you can fetch PHAssets like so (you can even limit results to include only photo assets):
        let onlyImagesOptions = PHFetchOptions()
        onlyImagesOptions.predicate = NSPredicate(format: "mediaType = %i", PHAssetMediaType.Image.rawValue)
        if let result = PHAsset.fetchKeyAssetsInAssetCollection(collection, options: onlyImagesOptions) {
            print("Images count: \(result.count)")
        }
    }
})

// *** 3 ***
// Get smart albums
let smartAlbums = PHAssetCollection.fetchAssetCollectionsWithType(.SmartAlbum, subtype: .AlbumRegular, options: nil) // Here you can specify Photostream, etc. as PHAssetCollectionSubtype.xxx
smartAlbums.enumerateObjectsUsingBlock( {
    if let assetCollection = $0.0 as? PHAssetCollection {
        print("album title: \(assetCollection.localizedTitle)")
        // One thing to note with Smart Albums is that collection.estimatedAssetCount can return NSNotFound if estimatedAssetCount cannot be determined. As title suggest this is estimated. If you want to be sure of number of assets you have to perform fetch and get the count like:

        let assetsFetchResult = PHAsset.fetchAssetsInAssetCollection(assetCollection, options: nil)
        let numberOfAssets = assetsFetchResult.count
        let estimatedCount =  (assetCollection.estimatedAssetCount == NSNotFound) ? -1 : assetCollection.estimatedAssetCount
        print("Assets count: \(numberOfAssets), estimate: \(estimatedCount)")
    }
})

Answer 3

试试这个代码...

self.imageArray=[[NSArray alloc] init];

PHImageRequestOptions *requestOptions = [[PHImageRequestOptions alloc] init];
requestOptions.resizeMode   = PHImageRequestOptionsResizeModeExact;
requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
requestOptions.synchronous = true;
PHFetchResult *result = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:nil];

NSLog(@"%d",(int)result.count);

    PHImageManager *manager = [PHImageManager defaultManager];
    NSMutableArray *images = [NSMutableArray arrayWithCapacity:countValue];

    // assets contains PHAsset objects.

    __block UIImage *ima;
    for (PHAsset *asset in result) {
        // Do something with the asset

        [manager requestImageForAsset:asset
                           targetSize:PHImageManagerMaximumSize
                          contentMode:PHImageContentModeDefault
                              options:requestOptions
                        resultHandler:^void(UIImage *image, NSDictionary *info) {
                            ima = image;

                            [images addObject:ima];

                        }];




    self.imageArray = [images copy];