Firestore: Use foundation API instead of C API (#12264)

Author: dconeybe

Firestore/core/src/util/filesystem_apple.mm

@@ -22,6 +22,7 @@
 
 #include "Firestore/core/src/util/path.h"
 #include "Firestore/core/src/util/statusor.h"
+#include "Firestore/core/src/util/string_format.h"
 #include "absl/strings/str_cat.h"
 
 namespace firebase {
@@ -90,6 +91,24 @@
   return Path::FromUtf8("/tmp");
 }
 
+Status Filesystem::IsDirectory(const Path& path) {
+  NSFileManager* file_manager = NSFileManager.defaultManager;
+  NSString* ns_path_str = path.ToNSString();
+  BOOL is_directory = NO;
+
+  if (![file_manager fileExistsAtPath:ns_path_str isDirectory:&is_directory]) {
+    return Status{Error::kErrorNotFound, path.ToUtf8String()};
+  }
+
+  if (!is_directory) {
+    return Status{Error::kErrorFailedPrecondition,
+                  StringFormat("Path %s exists but is not a directory",
+                               path.ToUtf8String())};
+  }
+
+  return Status::OK();
+}
+
 }  // namespace util
 }  // namespace firestore
 }  // namespace firebase

Firestore/core/src/util/filesystem_posix.cc

@@ -130,6 +130,7 @@ Path Filesystem::TempDir() {
 }
 #endif  // !__APPLE__ && !_WIN32
 
+#if !__APPLE__
 Status Filesystem::IsDirectory(const Path& path) {
   struct stat buffer {};
   if (::stat(path.c_str(), &buffer)) {
@@ -165,6 +166,7 @@ Status Filesystem::IsDirectory(const Path& path) {
 
   return Status::OK();
 }
+#endif  // !__APPLE__
 
 StatusOr<int64_t> Filesystem::FileSize(const Path& path) {
   struct stat st {};