Clean up framework support

This is an NFC, as it supports both the pre- and post- cleanup APIs.

RELNOTES: None
PiperOrigin-RevId: 240998664

lib/framework_migration.bzl

@@ -0,0 +1,28 @@
+# Copyright 2019 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helper functions related to apple framework cleanup migration."""
+
+def _is_post_framework_migration():
+    """Determine whether bazel is pre- or post- framework infrastructure migration.
+
+    Returns:
+        Whether bazel has been updated to use the new framework infrastructure.
+    """
+
+    return hasattr(apple_common.new_objc_provider(), "static_framework_names")
+
+framework_migration = struct(
+    is_post_framework_migration = _is_post_framework_migration,
+)