PHAssetCollectionSubtype 类型说明

通过以下方法获取相册图片：

+ (PHFetchResult<PHAssetCollection *> *)fetchAssetCollectionsWithType:(PHAssetCollectionType)type subtype:(PHAssetCollectionSubtype)subtype options:(nullable PHFetchOptions *)options;

PHAssetCollectionType类型：

typedef NS_ENUM(NSInteger, PHAssetCollectionType) {
    PHAssetCollectionTypeAlbum      = 1, // 用户自定义相册
    PHAssetCollectionTypeSmartAlbum = 2, // 系统相册
    PHAssetCollectionTypeMoment     API_DEPRECATED("Will be removed in a future release", ios(8, 13), tvos(10, 13)) API_UNAVAILABLE(macos) = 3, // 系统相册，按照每日区分
};

选择相册类型为PHAssetCollectionTypeAlbum(用户自定义相册)时：

typedef NS_ENUM(NSInteger, PHAssetCollectionSubtype) {
    // PHAssetCollectionTypeAlbum regular subtypes
    PHAssetCollectionSubtypeAlbumRegular         = 2,// 所有自定义相册
    PHAssetCollectionSubtypeAlbumSyncedEvent     = 3,// 空
    PHAssetCollectionSubtypeAlbumSyncedFaces     = 4,// 空
    PHAssetCollectionSubtypeAlbumSyncedAlbum     = 5,// 空
    PHAssetCollectionSubtypeAlbumImported        = 6,// 空
    
    // PHAssetCollectionTypeAlbum shared subtypes
    PHAssetCollectionSubtypeAlbumMyPhotoStream   = 100,// 空
    PHAssetCollectionSubtypeAlbumCloudShared     = 101,// 空
    
    // PHAssetCollectionTypeSmartAlbum subtypes
    PHAssetCollectionSubtypeSmartAlbumGeneric    = 200,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumPanoramas  = 201,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumVideos     = 202,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumFavorites  = 203,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumTimelapses = 204,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumAllHidden  = 205,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumRecentlyAdded = 206,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumBursts     = 207,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumSlomoVideos = 208,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumUserLibrary = 209,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumSelfPortraits API_AVAILABLE(ios(9)) = 210,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumScreenshots API_AVAILABLE(ios(9)) = 211,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumDepthEffect API_AVAILABLE(macos(10.13), ios(10.2), tvos(10.1)) = 212,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumLivePhotos API_AVAILABLE(macos(10.13), ios(10.3), tvos(10.2)) = 213,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumAnimated API_AVAILABLE(macos(10.15), ios(11), tvos(11)) = 214,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumLongExposures API_AVAILABLE(macos(10.15), ios(11), tvos(11)) = 215,// 所有自定义相册
    PHAssetCollectionSubtypeSmartAlbumUnableToUpload API_AVAILABLE(macos(10.15), ios(13), tvos(13)) = 216,// 所有自定义相册

    // Used for fetching, if you don't care about the exact subtype
    PHAssetCollectionSubtypeAny = NSIntegerMax// 所有自定义相册
};

选择相册类型为PHAssetCollectionTypeSmartAlbum(系统相册)时：

所有系统相册：全景照片、动图、最近删除、无法上传、慢动作、截屏、已隐藏、个人收藏、自拍、连拍快照、最近项目、实况照片、视频、最近添加、延时摄影、长曝光、人像。

typedef NS_ENUM(NSInteger, PHAssetCollectionSubtype) {
    // PHAssetCollectionTypeAlbum regular subtypes
    PHAssetCollectionSubtypeAlbumRegular         = 2,// 所有系统相册
    PHAssetCollectionSubtypeAlbumSyncedEvent     = 3,// 所有系统相册
    PHAssetCollectionSubtypeAlbumSyncedFaces     = 4,// 所有系统相册
    PHAssetCollectionSubtypeAlbumSyncedAlbum     = 5,// 所有系统相册
    PHAssetCollectionSubtypeAlbumImported        = 6,// 所有系统相册
    
    // PHAssetCollectionTypeAlbum shared subtypes
    PHAssetCollectionSubtypeAlbumMyPhotoStream   = 100,// 所有系统相册
    PHAssetCollectionSubtypeAlbumCloudShared     = 101,// 所有系统相册
    
    // PHAssetCollectionTypeSmartAlbum subtypes
    PHAssetCollectionSubtypeSmartAlbumGeneric    = 200,// 没有任何数据
    PHAssetCollectionSubtypeSmartAlbumPanoramas  = 201,// 全景照片
    PHAssetCollectionSubtypeSmartAlbumVideos     = 202,// 视频
    PHAssetCollectionSubtypeSmartAlbumFavorites  = 203,// 个人收藏
    PHAssetCollectionSubtypeSmartAlbumTimelapses = 204,// 延时摄影
    PHAssetCollectionSubtypeSmartAlbumAllHidden  = 205,// 已隐藏
    PHAssetCollectionSubtypeSmartAlbumRecentlyAdded = 206,// 最近添加
    PHAssetCollectionSubtypeSmartAlbumBursts     = 207,// 连拍快照
    PHAssetCollectionSubtypeSmartAlbumSlomoVideos = 208,// 慢动作
    PHAssetCollectionSubtypeSmartAlbumUserLibrary = 209,// 最近项目
    PHAssetCollectionSubtypeSmartAlbumSelfPortraits API_AVAILABLE(ios(9)) = 210,// 自拍
    PHAssetCollectionSubtypeSmartAlbumScreenshots API_AVAILABLE(ios(9)) = 211,// 截屏
    PHAssetCollectionSubtypeSmartAlbumDepthEffect API_AVAILABLE(macos(10.13), ios(10.2), tvos(10.1)) = 212,// 人像
    PHAssetCollectionSubtypeSmartAlbumLivePhotos API_AVAILABLE(macos(10.13), ios(10.3), tvos(10.2)) = 213,// 实况照片
    PHAssetCollectionSubtypeSmartAlbumAnimated API_AVAILABLE(macos(10.15), ios(11), tvos(11)) = 214,// 动图
    PHAssetCollectionSubtypeSmartAlbumLongExposures API_AVAILABLE(macos(10.15), ios(11), tvos(11)) = 215,// 长曝光
    PHAssetCollectionSubtypeSmartAlbumUnableToUpload API_AVAILABLE(macos(10.15), ios(13), tvos(13)) = 216,// 无法上传

    // Used for fetching, if you don't care about the exact subtype
    PHAssetCollectionSubtypeAny = NSIntegerMax// 全景照片、动图、慢动作、截屏、已隐藏、个人收藏、自拍、连拍快照、最近项目、实况照片、视频、延时摄影、长曝光、人像（少了这三个：最近删除、无法上传、最近添加）
};

选择相册类型为PHAssetCollectionTypeMoment(系统相册)时：

返回"最近项目"中的所有相片，按照每日区分，选任意PHAssetCollectionSubtype结果不变

以上为自身测试，如有问题可发私信

苹果源文档：https://developer.apple.com/documentation/photokit/phassetcollectionsubtype