Swift dummy phase fix

PiperOrigin-RevId: 218535295
diff --git a/src/TulsiGenerator/PBXTargetGenerator.swift b/src/TulsiGenerator/PBXTargetGenerator.swift
index 4bf101d..f92081d 100644
--- a/src/TulsiGenerator/PBXTargetGenerator.swift
+++ b/src/TulsiGenerator/PBXTargetGenerator.swift
@@ -1576,6 +1576,7 @@
         "SUFFIXES=(swiftdoc swiftmodule)\n" +
         "for ARCH in \"${ARCH_ARRAY[@]}\"\n" +
         "do\n" +
+        "  mkdir -p \"$OBJECT_FILE_DIR_normal/$ARCH/\"\n" +
         "  touch \"$OBJECT_FILE_DIR_normal/$ARCH/$SWIFT_OBJC_INTERFACE_HEADER_NAME\"\n" +
         "  for SUFFIX in \"${SUFFIXES[@]}\"\n" +
         "  do\n" +