use Documents folder visible from Files app for save data

desktop_version/CMakeLists.txt

@@ -145,7 +145,8 @@ elseif(CMAKE_SYSTEM_NAME STREQUAL "iOS")
         XCODE_ATTRIBUTE_MARKETING_VERSION "2.4"
         XCODE_ATTRIBUTE_ASSETCATALOG_COMPILER_APPICON_NAME AppIcon
         XCODE_ATTRIBUTE_GENERATE_INFOPLIST_FILE YES
-        XCODE_ATTRIBUTE_INFOPLIST_FILE ""
+        MACOSX_BUNDLE_INFO_PLIST "${CMAKE_CURRENT_SOURCE_DIR}/Info.plist"
+        XCODE_ATTRIBUTE_INFOPLIST_KEY_LSSupportsOpeningDocumentsInPlace YES
         RESOURCE "${DATA_ZIP};AppIcon.xcassets"
     )
 

desktop_version/Info.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>UIFileSharingEnabled</key>
+	<true/>
+</dict>
+</plist>

desktop_version/src/FileSystemUtils.cpp

@@ -1330,6 +1330,19 @@ static int PLATFORM_getOSDirectory(char* output, const size_t output_size)
     }
     SDL_snprintf(output, output_size, "%s/", externalStoragePath);
     return 1;
+#elif defined(TARGET_OS_IPHONE)
+    // (ab)use SDL APIs to get the path to the Documents folder without needing Objective-C
+    const char* prefsPath = SDL_GetPrefPath("", "");
+    if (prefsPath == NULL)
+    {
+        vlog_error(
+            "Could not get OS directory: %s",
+            SDL_GetError()
+        );
+        return 0;
+    }
+    SDL_snprintf(output, output_size, "%s/../../Documents/", prefsPath);
+    return 1;
 #else
     const char* prefDir = PHYSFS_getPrefDir("distractionware", "VVVVVV");
     if (prefDir == NULL)