This page shows you how to enable App Check in an Apple app, using your custom App Check provider. When you enable App Check, you help ensure that only your app can access your project's Firebase resources.
If you want to use App Check with the built-in providers, see the docs for App Check with App Attest and App Check with DeviceCheck.
Before you begin
Add Firebase to your Apple project if you haven’t already done so.
Implement your custom App Check provider's server-side logic.
1. Add the App Check library to your app
Add the dependency for App Check to your project's
Podfile
:pod 'FirebaseAppCheck'
Or, alternatively, you can use Swift Package Manager instead.
Also, make sure you're using the latest version of any Firebase service client libraries you depend on.
Run
pod install
and open the created.xcworkspace
file.
2. Implement the App Check protocols
First, you need to create classes that implement the AppCheckProvider
and
AppCheckProviderFactory
protocols.
Your AppCheckProvider
class must have a getToken(completion:)
method, which
collects whatever information your custom App Check provider requires as
proof of authenticity, and sends it to your token acquisition service in
exchange for an App Check token. The App Check SDK handles token
caching, so always get a new token in your implementation of
getToken(completion:)
.
Swift
class YourCustomAppCheckProvider: NSObject, AppCheckProvider { var app: FirebaseApp init(withFirebaseApp app: FirebaseApp) { self.app = app super.init() } func getToken(completion handler: @escaping (AppCheckToken?, Error?) -> Void) { DispatchQueue.main.async { // Logic to exchange proof of authenticity for an App Check token. // ... // Create AppCheckToken object. let exp = Date(timeIntervalSince1970: expirationFromServer) let token = AppCheckToken( token: tokenFromServer, expirationDate: exp ) // Pass the token or error to the completion handler. handler(token, nil) } } }
Objective-C
@interface YourCustomAppCheckProvider : NSObject <FIRAppCheckProvider> @property FIRApp *app; - (id)initWithApp:(FIRApp *)app; @end @implementation YourCustomAppCheckProvider - (id)initWithApp:app { self = [super init]; if (self) { self.app = app; } return self; } - (void)getTokenWithCompletion:(nonnull void (^)(FIRAppCheckToken * _Nullable, NSError * _Nullable))handler { dispatch_async(dispatch_get_main_queue(), ^{ // Logic to exchange proof of authenticity for an App Check token. // ... // Create FIRAppCheckToken object. NSTimeInterval exp = expirationFromServer; FIRAppCheckToken *token = [[FIRAppCheckToken alloc] initWithToken:tokenFromServer expirationDate:[NSDate dateWithTimeIntervalSince1970:exp]]; // Pass the token or error to the completion handler. handler(token, nil); }); } @end
Also, implement a AppCheckProviderFactory
class that creates instances of your
AppCheckProvider
implementation:
Swift
class YourCustomAppCheckProviderFactory: NSObject, AppCheckProviderFactory { func createProvider(with app: FirebaseApp) -> AppCheckProvider? { return YourCustomAppCheckProvider(withFirebaseApp: app) } }
Objective-C
@interface YourCustomAppCheckProviderFactory : NSObject <FIRAppCheckProviderFactory> @end @implementation YourCustomAppCheckProviderFactory - (nullable id<FIRAppCheckProvider>)createProviderWithApp:(FIRApp *)app { return [[YourCustomAppCheckProvider alloc] initWithApp:app]; } @end
3. Initialize App Check
Add the following initialization code to your app delegate or app initializer:
Swift
let providerFactory = YourAppCheckProviderFactory() AppCheck.setAppCheckProviderFactory(providerFactory) FirebaseApp.configure()
Objective-C
YourAppCheckProviderFactory *providerFactory = [[YourAppCheckProviderFactory alloc] init]; [FIRAppCheck setAppCheckProviderFactory:providerFactory]; [FIRApp configure];
Once the App Check library is installed in your app, start distributing the updated app to your users.
The updated client app will begin sending App Check tokens along with every request it makes to Firebase, but Firebase products will not require the tokens to be valid until you enable enforcement in the App Check section of the Firebase console. See the next two sections for details.
4. Monitor request metrics
Now that your updated app is in the hands of users, you can enable enforcement of App Check for the Firebase products you use. Before you do so, however, you should make sure that doing so won’t disrupt your existing legitimate users.
Realtime Database, Cloud Firestore, and Cloud Storage
An important tool you can use to make this decision for Realtime Database, Cloud Firestore, and Cloud Storage is the App Check request metrics screen.
To view the App Check request metrics for a product, open the App Check section of the Firebase console. For example:
The request metrics for each product are broken down into four categories:
Verified requests are those that have a valid App Check token. After you enable App Check enforcement, only requests in this category will succeed.
Outdated client requests are those that are missing an App Check token. These requests might be from an older version of the Firebase SDK before App Check was included in the app.
Unknown origin requests are those that are missing an App Check token, and don't look like they come from the Firebase SDK. These might be from requests made with stolen API keys or forged requests made without the Firebase SDK.
Invalid requests are those that have an invalid App Check token, which might be from an inauthentic client attempting to impersonate your app, or from emulated environments.
The distribution of these categories for your app should inform when you decide to enable enforcement. Here are some guidelines:
If almost all of the recent requests are from verified clients, consider enabling enforcement to start protecting your backend resources.
If a significant portion of the recent requests are from likely-outdated clients, to avoid disrupting users, consider waiting for more users to update your app before enabling enforcement. Enforcing App Check on a released app will break prior app versions that are not integrated with the App Check SDK.
If your app hasn't launched yet, you should enable App Check enforcement immediately, since there aren't any outdated clients in use.
Cloud Functions
For Cloud Functions, you can get App Check metrics by examining your functions' logs. Every invocation of a callable function emits a structured log entry like the following example:
{
"severity": "INFO", // INFO, WARNING, or ERROR
"logging.googleapis.com/labels": {"firebase-log-type": "callable-request-verification"},
"jsonPayload": {
"message": "Callable header verifications passed.",
"verifications": {
// ...
"app": "MISSING", // VALID, INVALID, or MISSING
}
}
}
You can analyze these metrics in the Google Cloud Console by creating a logs-based counter metric with the following metric filter:
resource.type="cloud_function" resource.labels.function_name="YOUR_CLOUD_FUNCTION" resource.labels.region="us-central1" labels.firebase-log-type="callable-request-verification"
Label the metric
using the field jsonPayload.verifications.appCheck
.
5. Enable enforcement
To enable enforcement, follow the instructions for each product, below. Once you enable enforcement for a product, all unverified requests to that product will be rejected.
Realtime Database, Cloud Firestore, and Cloud Storage
To enable enforcement for Realtime Database, Cloud Firestore (iOS and Android), and Cloud Storage:
Open the App Check section of the Firebase console.
Expand the metrics view of the product for which you want to enable enforcement.
Click Enforce and confirm your choice.
Note that it can take up to 15 minutes after you enable enforcement for it to take effect.
Cloud Functions
See Enable App Check enforcement for Cloud Functions.