Connect an Apple app

Each Firebase Apple SDK has a useEmulator(withHost:port:) method. Call it once for each product, right after FirebaseApp.configure() and before the app uses Firebase. The same code serves iOS, iPadOS and macOS apps.

Connect

Swift

ShopApp.swift

import FirebaseAuth
import FirebaseCore
import FirebaseFirestore
import FirebaseFunctions
import FirebaseStorage
import SwiftUI

@main
struct ShopApp: App {
    init() {
        FirebaseApp.configure()
        #if DEBUG
        let host = "127.0.0.1"
        Auth.auth().useEmulator(withHost: host, port: 9099)

        let db = Firestore.firestore()
        db.useEmulator(withHost: host, port: 8080)
        let settings = db.settings
        settings.isSSLEnabled = false
        settings.cacheSettings = MemoryCacheSettings()
        db.settings = settings

        Storage.storage().useEmulator(withHost: host, port: 9199)
        Functions.functions().useEmulator(withHost: host, port: 5001)
        #endif
    }

    var body: some Scene {
        WindowGroup { ContentView() }
    }
}

Objective-C

AppDelegate.m

@import FirebaseAuth;
@import FirebaseCore;
@import FirebaseFirestore;
@import FirebaseFunctions;
@import FirebaseStorage;

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [FIRApp configure];
#if DEBUG
  NSString *host = @"127.0.0.1";
  [[FIRAuth auth] useEmulatorWithHost:host port:9099];

  FIRFirestore *db = [FIRFirestore firestore];
  [db useEmulatorWithHost:host port:8080];
  FIRFirestoreSettings *settings = db.settings;
  settings.sslEnabled = NO;
  settings.cacheSettings = [[FIRMemoryCacheSettings alloc] init];
  db.settings = settings;

  [[FIRStorage storage] useEmulatorWithHost:host port:9199];
  [[FIRFunctions functions] useEmulatorWithHost:host port:5001];
#endif
  return YES;
}

#if DEBUG keeps the calls out of release builds. Use the ports from your firebase.json if they are not the defaults; the console’s Connect dialog prints the Swift lines with your ports filled in.

Firestore needs two settings more. On Apple platforms, Firestore’s useEmulator sets only the host: SSL stays on, and the emulator does not speak SSL. Turn it off in Firestore’s settings, as Google’s own sample does. The memory cache is optional. Firestore’s offline cache is not cleared when the emulator’s data changes, and without --keep-data every Firenook start is empty, so a memory cache keeps the last run’s documents from showing up.

If your functions run in another region, connect that region’s instance: Functions.functions(region: "europe-west1").

A demo project without GoogleService-Info.plist

A demo- project needs no configuration file. Configure Firebase with options like these, the ones the console’s Apple snippet prints:

Swift

let options = FirebaseOptions(googleAppID: "1:000000000000:ios:0000000000000000",
                              gcmSenderID: "0")
options.apiKey = "demo-api-key"
options.projectID = "demo-shop"
options.storageBucket = "demo-shop.appspot.com"
FirebaseApp.configure(options: options)

Objective-C

FIROptions *options =
    [[FIROptions alloc] initWithGoogleAppID:@"1:000000000000:ios:0000000000000000"
                                GCMSenderID:@"0"];
options.APIKey = @"demo-api-key";
options.projectID = @"demo-shop";
options.storageBucket = @"demo-shop.appspot.com";
[FIRApp configureWithOptions:options];

The project id must be the one Firenook runs with, and the storage bucket is <project id>.appspot.com. The app id only has to have the shape the SDK checks for. With a real project, keep GoogleService-Info.plist and plain FirebaseApp.configure().

Simulator or device

Where the app runs	Host
The iOS Simulator, or a Mac app	127.0.0.1
An iPhone or iPad	Your Mac’s network address, with Firenook started with --host 0.0.0.0

The Simulator shares your Mac’s network, so 127.0.0.1 is your Mac. A device needs your Mac’s address, and Firenook must listen on the network:

npx firenook emulators:start --host 0.0.0.0

Firenook has no authentication: with --host 0.0.0.0, anyone on the network can reach the emulators and the data, so use it only on a network you trust.

App Transport Security

Authentication, Storage and Functions requests are plain HTTP, which App Transport Security governs. Since iOS 17 and macOS 14, it no longer allows connections to IP addresses by default. Add NSAllowsLocalNetworking, which allows plain connections to IP addresses, .local names and names without a domain:

Info.plist

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsLocalNetworking</key>
    <true/>
</dict>

On a device, the first connection to your Mac’s address also asks the user for Local Network access. Add a reason for that prompt; the Simulator never shows it:

Info.plist

<key>NSLocalNetworkUsageDescription</key>
<string>Connects to the Firebase emulators on your development Mac.</string>

Next

Building for Android too? See Android. For cross-platform apps, see Flutter or React Native.