新增景区排队管理功能

suixinkan/Features/ScenicQueue/Services/ScenicQueueQRCodeSaver.swift

@@ -0,0 +1,55 @@
+//
+//  ScenicQueueQRCodeSaver.swift
+//  suixinkan
+//
+
+import Foundation
+import Photos
+import UIKit
+
+/// 排队二维码保存服务。
+enum ScenicQueueQRCodeSaver {
+    /// 下载二维码图片并保存到系统相册。
+    static func saveImage(from urlString: String) async throws {
+        guard let url = URL(string: urlString) else {
+            throw ScenicQueueQRCodeSaverError.invalidURL
+        }
+        let (data, _) = try await URLSession.shared.data(from: url)
+        guard let image = UIImage(data: data) else {
+            throw ScenicQueueQRCodeSaverError.invalidImage
+        }
+        try await saveToPhotoLibrary(image)
+    }
+
+    private static func saveToPhotoLibrary(_ image: UIImage) async throws {
+        let status = PHPhotoLibrary.authorizationStatus(for: .addOnly)
+        if status == .notDetermined {
+            _ = await PHPhotoLibrary.requestAuthorization(for: .addOnly)
+        }
+        guard PHPhotoLibrary.authorizationStatus(for: .addOnly) == .authorized
+                || PHPhotoLibrary.authorizationStatus(for: .addOnly) == .limited else {
+            throw ScenicQueueQRCodeSaverError.denied
+        }
+        try await PHPhotoLibrary.shared().performChanges {
+            PHAssetChangeRequest.creationRequestForAsset(from: image)
+        }
+    }
+}
+
+/// 排队二维码保存错误。
+enum ScenicQueueQRCodeSaverError: LocalizedError {
+    case invalidURL
+    case invalidImage
+    case denied
+
+    var errorDescription: String? {
+        switch self {
+        case .invalidURL:
+            "服务端返回的二维码地址无效"
+        case .invalidImage:
+            "下载或保存二维码失败，请检查网络与存储权限"
+        case .denied:
+            "未授予权限，无法将小程序码保存到相册"
+        }
+    }
+}