Flutter IOS 图片保存相册权限 NSPhotoLibraryAddUsageDescription 配置如下:
路径为 ios/Runner/Info.plist
<key>NSCameraUsageDescription</key>
<string>请允许APP访问您的相机</string>
<key>NSPhotoLibraryAddUsageDescription</key>
<string>请允许APP保存图片到相册</string>
<key>NSPhotoLibraryUsageDescription</key>
<string>请允许APP访问您的相册</string>