CB-7995: document that `FileTransferError.exception` on iOS is never defined.
diff --git a/README.md b/README.md
index 6bdbfd5..bcfc26a 100644
--- a/README.md
+++ b/README.md
@@ -308,6 +308,10 @@
 
 - __exception__: Either e.getMessage or e.toString (String)
 
+### iOS Quirks
+
+__exception__ is never defined.
+
 ### Constants
 
 - 1 = `FileTransferError.FILE_NOT_FOUND_ERR`