feat(): implemented fetch all assets property wrapper; refactor(album): use fetch all assets property wrapper

Author: Christian Elies

Sources/MediaCore/API/Album/Album.swift

@@ -11,8 +11,6 @@ import Photos
 /// Convenience wrapper type around `PHAssetCollection`
 ///
 public struct Album {
-    static var phAsset: PHAsset.Type = PHAsset.self
-
     let phAssetCollectionWrapper: PHAssetCollectionWrapper
 
     var phAssetCollection: PHAssetCollection? { phAssetCollectionWrapper.value }
@@ -58,6 +56,12 @@ public struct Album {
     @FetchAssets
     public var livePhotos: [LivePhoto]
 
+    /// All media (audios, live photos, photos, videos and more?) contained in the receiver
+    /// sorted by `creationDate descending`.
+    ///
+    @FetchAllAssets
+    public var allMedia: [AnyMedia]
+
     init(phAssetCollection: PHAssetCollection) {
         _audios = FetchAssets(in: phAssetCollection, sort: [Media.Sort(key: .creationDate, ascending: false)])
         _photos = FetchAssets(in: phAssetCollection, sort: [Media.Sort(key: .creationDate, ascending: false)])
@@ -67,31 +71,11 @@ public struct Album {
             filter: [.mediaSubtypes([.live])],
             sort: [Media.Sort(key: .creationDate, ascending: false)]
         )
+        _allMedia = FetchAllAssets(in: phAssetCollection, sort: [Media.Sort(key: .creationDate, ascending: false)])
         phAssetCollectionWrapper = PHAssetCollectionWrapper(phAssetCollection: phAssetCollection)
     }
 }
 
-public extension Album {
-    /// All media (audios, live photos, photos, videos and more?) contained in the receiver
-    /// sorted by `creationDate descending`
-    ///
-    var allMedia: [AnyMedia] {
-        guard let phAssetCollection = phAssetCollection else { return [] }
-
-        let options = PHFetchOptions()
-        options.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
-        let result = Self.phAsset.fetchAssets(in: phAssetCollection, options: options)
-        var media: [AnyMedia] = []
-        result.enumerateObjects { asset, _, _ in
-            guard let anyMedia = asset.anyMedia else {
-                return
-            }
-            media.append(anyMedia)
-        }
-        return media
-    }
-}
-
 public extension Album {
     /// Creates an album with the given title
     ///

Sources/MediaCore/API/PropertyWrappers/FetchAllAssets.swift

@@ -0,0 +1,77 @@
+//
+//  FetchAllAssets.swift
+//  MediaCore
+//
+//  Created by Christian Elies on 13.02.21.
+//
+
+import Photos
+
+/// Property wrapper for fetching all assets from the photo library.
+/// Fetches the assets lazily (after accessing the property).
+///
+@propertyWrapper
+public struct FetchAllAssets {
+    static var phAsset: PHAsset.Type = PHAsset.self
+
+    private var assetCollection: PHAssetCollection?
+    private let options = PHFetchOptions()
+    private let defaultSort: Media.Sort<Media.SortKey> = Media.Sort(key: .creationDate, ascending: false)
+
+    /// Wrapped array of `AnyMedia` instances.
+    public var wrappedValue: [AnyMedia] {
+        let result: PHFetchResult<PHAsset>
+        if let assetCollection = assetCollection {
+            result = Self.phAsset.fetchAssets(in: assetCollection, options: options)
+        } else {
+            result = Self.phAsset.fetchAssets(with: options)
+        }
+        var media: [AnyMedia] = []
+        result.enumerateObjects { asset, _, _ in
+            guard let anyMedia = asset.anyMedia else {
+                return
+            }
+            media.append(anyMedia)
+        }
+        return media
+    }
+
+    /// Initializes the property wrapper using a default sort descriptor
+    /// (sort by `creationDate descending`).
+    ///
+    public init() {
+        options.sortDescriptors = [defaultSort.sortDescriptor]
+    }
+
+    /// Initializes the property wrapper using the given sort descriptors
+    /// to define the `PHFetchOptions`.
+    ///
+    /// - Parameters:
+    ///   - assetCollection: limits the fetch to a specific asset collection, by default all assets in the library are taken into account.
+    ///   - sort: a set of `Sort<MediaSortKey>` for sorting the assets
+    ///   - fetchLimit: a maximum number of results to fetch, defaults to 0 (no limit)
+    ///   - includeAllBurstAssets: a Boolean value that determines whether the fetch result includes all assets from burst photo sequences, defaults to false
+    ///   - includeHiddenAssets: a Boolean value that determines whether the fetch result includes assets marked as hidden, defaults to false
+    ///
+    public init(
+        in assetCollection: PHAssetCollection? = nil,
+        sort: Set<Media.Sort<Media.SortKey>> = [],
+        fetchLimit: Int = 0,
+        includeAllBurstAssets: Bool = false,
+        includeHiddenAssets: Bool = false
+    ) {
+        self.assetCollection = assetCollection
+
+        var sortKeys = sort
+        sortKeys.insert(defaultSort)
+
+        if !sortKeys.isEmpty {
+            let sortDescriptors = sortKeys.map { $0.sortDescriptor }
+            options.sortDescriptors = sortDescriptors
+        }
+
+        options.fetchLimit = fetchLimit
+        options.includeAllBurstAssets = includeAllBurstAssets
+        options.includeHiddenAssets = includeHiddenAssets
+    }
+}

Tests/MediaTests/Models/Album/AlbumTests.swift

@@ -13,7 +13,7 @@ final class AlbumTests: XCTestCase {
     lazy var album = Album(phAssetCollection: mockAssetCollection)
 
     override func setUp() {
-        Album.phAsset = MockPHAsset.self
+        FetchAllAssets.phAsset = MockPHAsset.self
         PHAssetFetcher.asset = MockPHAsset.self
         MockPHAsset.fetchResult.mockAssets.removeAll()
         AlbumFetcher.assetCollection = MockPHAssetCollection.self