Found a nice solution on how to avoid "-load-all" linker flag.https://github.com/square/KIF/blob/master/Additions/LoadableCategory.h
Just quoting here:
// Created by Karl Stenerud on 7/16/11.
// Licensed to Square, Inc. under one or more contributor license agreements.
// See the LICENSE file distributed with this work for the terms under
// which Square, Inc. licenses this file to you.
/** Make all categories in the current file loadable without using -load-all.
* Normally, compilers will skip linking files that contain only categories.
* Adding a call to this macro adds a dummy class, which causes the linker
* to add the file.
* @param UNIQUE_NAME A globally unique name.
#define MAKE_CATEGORIES_LOADABLE(UNIQUE_NAME) @interface FORCELOAD_##UNIQUE_NAME @end @implementation FORCELOAD_##UNIQUE_NAME @end