firebase-ios-sdk/Example/Database/App/iOS/FIRAppDelegate.m

// 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 "FIRAppDelegate.h"

@implementation FIRAppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  // Override point for customization after application launch.
  return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application {
  // Sent when the application is about to move from active to inactive state. This can occur for
  // certain types of temporary interruptions (such as an incoming phone call or SMS message) or
  // when the user quits the application and it begins the transition to the background state. Use
  // this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates.
  // Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
  // Use this method to release shared resources, save user data, invalidate timers, and store
  // enough application state information to restore your application to its current state in case
  // it is terminated later. If your application supports background execution, this method is
  // called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
  // Called as part of the transition from the background to the inactive state; here you can undo
  // many of the changes made on entering the background.
}

- (void)applicationDidBecomeActive:(UIApplication *)application {
  // Restart any tasks that were paused (or not yet started) while the application was inactive. If
  // the application was previously in the background, optionally refresh the user interface.
}

- (void)applicationWillTerminate:(UIApplication *)application {
  // Called when the application is about to terminate. Save data if appropriate. See also
  // applicationDidEnterBackground:.
}

@end