--- /dev/null
+/*
+ * Copyright 2017 Google
+ *
+ * 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.
+ */
+
+#import <Foundation/Foundation.h>
+
+/**
+ * Register the device with Checkin Service and get back the `authID`, `secret token` etc. for the
+ * client. Checkin results are cached in the `FIRMessagingDefaultsManager` and periodically refreshed to
+ * prevent them from being stale. Each client needs to register with checkin before registering
+ * with FIRMessaging.
+ */
+@interface FIRMessagingCheckinService : NSObject
+
+@property(nonatomic, readonly, strong) NSString *deviceAuthID;
+@property(nonatomic, readonly, strong) NSString *secretToken;
+@property(nonatomic, readonly, strong) NSString *versionInfo;
+@property(nonatomic, readonly, assign) BOOL hasValidCheckinInfo;
+
+/**
+ * Verify if valid checkin preferences have been loaded in memory.
+ *
+ * @return YES if valid checkin preferences exist in memory else NO.
+ */
+- (BOOL)hasValidCheckinInfo;
+
+/**
+ * Try to load prefetched checkin preferences from the cache. This supports the use case where
+ * InstanceID library has already obtained a valid checkin and we should be using that.
+ *
+ * This should be used as a last gasp effort to retreive any cached checkin preferences before
+ * hitting the FIRMessaging backend to retrieve new preferences.
+ *
+ * Note this is only required because InstanceID and FIRMessaging both require checkin preferences which
+ * need to be synced with each other.
+ *
+ * @return YES if successfully loaded cached checkin preferences into memory else NO.
+ */
+- (BOOL)tryToLoadPrefetchedCheckinPreferences;
+
+@end