Added Metadata writing, metadat conversion to c++, and format detection performance tests;

Changed AudioFile.Format.Detector to an enum;
Swapped nullptr to kCFAllocatorDefault in CFDataCreate calls;
Added a convenience static method to create AudioMetadata::Picture in swift from CFData which fixes previous performance inefficiency;
Recompiled xcframeworks
Fixes #2

Author: IgorMuzyka

XCFrameworkPackage/CxxTagLibBridge.xcframework/ios-arm64/CxxTagLibBridge.framework/CxxTagLibBridge

@@ -3,9 +3,26 @@
 #import <CoreFoundation/CoreFoundation.h>
 #import <ImageIO/ImageIO.h>
 
+/// Creates `AudioMetadata::Picture` from `CFDataRef data`, `std::string description` and `Kind kind`.
+AudioMetadata::Picture AudioMetadata::Picture::create_from_CFData(
+    CFDataRef data,
+    std::string description,
+    Kind kind
+) {
+    const UInt8 *bytes = CFDataGetBytePtr(data);
+    CFIndex length = CFDataGetLength(data);
+    auto buffer = Picture::Bytes(bytes, bytes + length);
+    return {
+        .bytes = std::move(buffer),
+        .size = static_cast<unsigned int>(length),
+        .description = description,
+        .kind = kind
+    };
+}
+
 /// Attempts to extract `MIME type` from raw image `bytes`, if fails returns empty string.
 AudioMetadata::Picture::MIMEType AudioMetadata::Picture::mime_type() {
-    auto data = CFDataCreate(nullptr, reinterpret_cast<const UInt8*>(bytes.data()), size);
+    auto data = CFDataCreate(kCFAllocatorDefault, reinterpret_cast<const UInt8*>(bytes.data()), size);
     auto imageSource = CGImageSourceCreateWithData(data, nullptr);
     std::string mimeType;
     if (imageSource) {
@@ -30,7 +47,7 @@ AudioMetadata::Picture::MIMEType AudioMetadata::Picture::mime_type() {
 /// Attempts to extract `MIME type, pixel width & height, color depth` from raw image `bytes`,
 /// if fails returns empty string and 0's.
 AudioMetadata::Picture::Properties AudioMetadata::Picture::properties() {
-    auto data = CFDataCreate(nullptr, reinterpret_cast<const UInt8*>(bytes.data()), size);
+    auto data = CFDataCreate(kCFAllocatorDefault, reinterpret_cast<const UInt8*>(bytes.data()), size);
     auto imageSource = CGImageSourceCreateWithData(data, nullptr);
     std::string mimeType;
     int width, height, depth;

XCFrameworkPackage/CxxTagLibBridge.xcframework/ios-arm64_x86_64-simulator/CxxTagLibBridge.framework/CxxTagLibBridge

@@ -1,5 +1,6 @@
 
 #import <swift/bridging>
+#import <CoreFoundation/CoreFoundation.h>
 #import <tuple>
 #import <string>
 #import <optional>
@@ -118,6 +119,9 @@ struct AudioMetadata final {
         using Properties = std::tuple<std::string, int, int, int>;
         Properties properties();
     public:
+        // MARK: - Convenience Constructor for Swift
+        static Picture create_from_CFData(CFDataRef data, std::string description, Kind kind);
+        
         // MARK: - Attached Picture: Format specific builders
         using FLACPicture = TagLib::FLAC::Picture *;
         FLACPicture convert_to_FLACPicture();

XCFrameworkPackage/Sources/CxxTagLibBridge/AudioMetadata/Picture/AudioMetadata.Picture+ImageIO.cpp

@@ -25,16 +25,7 @@ public extension AudioFile.Metadata {
         }
 
         var cxxRepresentation: AudioMetadata.Picture {
-            var picture = AudioMetadata.Picture();
-            #warning("this is rather slow & inefficient way to go from Data to [UInt8] to std::vector<char>")
-            /// take a look at [pointers to C](https://github.com/swiftlang/swift/blob/main/docs/HowSwiftImportsCAPIs.md#pointers-to-data).
-            var bytes = AudioMetadata.Picture.Bytes()
-            data.forEach { bytes.push_back(Int8(bitPattern: $0)) }
-            picture.bytes = bytes;
-            picture.size = UInt32(bytes.count);
-            picture.description = std.string(description)
-            picture.kind = kind.cxxRepresentation
-            return picture;
+            .create_from_CFData(data as CFData, std.string(description), kind.cxxRepresentation)
         }
     }
 }

XCFrameworkPackage/Sources/CxxTagLibBridge/include/CxxTagLibBridge/AudioMetadata.hpp

@@ -4,7 +4,7 @@ import class Foundation.FileHandle
 
 extension AudioFile.Format {
     /// Attempts to determine `AudioFile.Format` from given `URL`.
-    struct Detector {
+    enum Detector {
         static func format(at url: URL) throws(AudioFile.InitializationError) -> AudioFile.Format? {
             let fileExtension = url.pathExtension.lowercased()
             guard let fileHandle = try? FileHandle(forReadingFrom: url) else {

XCFrameworkPackage/Sources/SwiftTagLib/AttachedPicture.swift

@@ -8,32 +8,32 @@
 			<key>BinaryPath</key>
 			<string>SwiftTagLib.framework/SwiftTagLib</string>
 			<key>LibraryIdentifier</key>
-			<string>ios-arm64</string>
+			<string>ios-arm64_x86_64-simulator</string>
 			<key>LibraryPath</key>
 			<string>SwiftTagLib.framework</string>
 			<key>SupportedArchitectures</key>
 			<array>
 				<string>arm64</string>
+				<string>x86_64</string>
 			</array>
 			<key>SupportedPlatform</key>
 			<string>ios</string>
+			<key>SupportedPlatformVariant</key>
+			<string>simulator</string>
 		</dict>
 		<dict>
 			<key>BinaryPath</key>
 			<string>SwiftTagLib.framework/SwiftTagLib</string>
 			<key>LibraryIdentifier</key>
-			<string>ios-arm64_x86_64-simulator</string>
+			<string>ios-arm64</string>
 			<key>LibraryPath</key>
 			<string>SwiftTagLib.framework</string>
 			<key>SupportedArchitectures</key>
 			<array>
 				<string>arm64</string>
-				<string>x86_64</string>
 			</array>
 			<key>SupportedPlatform</key>
 			<string>ios</string>
-			<key>SupportedPlatformVariant</key>
-			<string>simulator</string>
 		</dict>
 	</array>
 	<key>CFBundlePackageType</key>