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    Get started with Firebase Remote Config


    You can use Firebase Remote Config to define parameters in your app and update their values in the cloud, allowing you to modify the appearance and behavior of your app without distributing an app update. This guide walks you through the steps to get started and provides some sample code, all of which is available to clone or download from the firebase/quickstart-ios GitHub repository.

    Step 1: Add Remote Config to your app

    1. If you haven't already, add Firebase to your Apple project .

    2. For Remote Config , Google Analytics is required for the conditional targeting of app instances to user properties and audiences. Make sure that you enable Google Analytics in your project.

    3. Create the singleton Remote Config object, as shown in the following example:

      Swift

       remoteConfig 
  
 = 
  
 RemoteConfig 
 . 
 remoteConfig 
 () 
 let 
  
 settings 
  
 = 
  
 RemoteConfigSettings 
 () 
 settings 
 . 
 minimumFetchInterval 
  
 = 
  
 0 
 remoteConfig 
 . 
 configSettings 
  
 = 
  
 settings 
       ViewController 

       
       
 . 
 swift

    Objective-C

     self 
 . 
 remoteConfig 
  
 = 
  
 [ 
 FIRRemoteConfig 
  
 remoteConfig 
 ]; 
 FIRRemoteConfigSettings 
  
 * 
 remoteConfigSettings 
  
 = 
  
 [[ 
 FIRRemoteConfigSettings 
  
 alloc 
 ] 
  
 init 
 ]; 
 remoteConfigSettings 
 . 
 minimumFetchInterval 
  
 = 
  
 0 
 ; 
 self 
 . 
 remoteConfig 
 . 
 configSettings 
  
 = 
  
 remoteConfigSettings 
 ; 
 
      ViewController 
 . 
 m

    This object is used to store in-app default parameter values, fetch updated parameter values from the Remote Config backend, and control when fetched values are made available to your app.

    During development, it's recommended to set a relatively low minimum fetch interval. See Throttling for more information.

    Step 2: Set in-app default parameter values

    You can set in-app default parameter values in the Remote Config object, so that your app behaves as intended before it connects to the Remote Config backend, and so that default values are available if none are set in the backend.

    1. Define a set of parameter names, and default parameter values using an NSDictionary object or a plist file .

      If you have already configured Remote Config backend parameter values, you can download a generated plist file that includes all default values and save it to your Xcode project.

      REST

      curl --compressed -D headers -H "Authorization: Bearer token 
-X GET https://firebaseremoteconfig.googleapis.com/v1/projects/ my-project-id 
/remoteConfig:downloadDefaults?format=PLIST -o RemoteConfigDefaults.plist

      You can generate a bearer token by running the following command using the Google Cloud CLI or Cloud Shell :

       gcloud  
auth  
print-access-token

      This token is short-lived, so you may need to regenerate it if you get an authentication error.

      Firebase console

      1. In the Parameters tab, open the Menu, and select Download default values.

      2. When prompted, enable .plist for iOS, then click Download file.

    2. Add these values to the Remote Config object using setDefaults: . The following example sets in-app default values from a plist file:

      Swift

       remoteConfig 
 . 
 setDefaults 
 ( 
 fromPlist 
 : 
  
 "RemoteConfigDefaults" 
 ) 
 
        ViewController 
 . 
 swift

      Objective-C

       [ 
 self 
 . 
 remoteConfig 
  
 setDefaultsFromPlistFileName 
 : 
 @"RemoteConfigDefaults" 
 ]; 
 
        ViewController 
 . 
 m

    Step 3: Get parameter values to use in your app

    Now you can get parameter values from the Remote Config object. If you later set values in the Remote Config backend, fetch them, and then activate them, those values are available to your app. Otherwise, you get the in-app parameter values configured using setDefaults: . To get these values, call the configValueForKey: method, providing the parameter key as an argument.

      let 
  
 remoteConfig 
  
 = 
  
 RemoteConfig 
 . 
 remoteConfig 
 () 
 // Retrieve a parameter value using configValueForKey 
 let 
  
 welcomeMessageValue 
  
 = 
  
 remoteConfig 
 . 
 configValue 
 ( 
 forKey 
 : 
  
 "welcome_message" 
 ) 
 let 
  
 welcomeMessage 
  
 = 
  
 welcomeMessageValue 
 . 
 stringValue 
 let 
  
 featureFlagValue 
  
 = 
  
 remoteConfig 
 . 
 configValue 
 ( 
 forKey 
 : 
  
 "new_feature_flag" 
 ) 
 let 
  
 isFeatureEnabled 
  
 = 
  
 featureFlagValue 
 . 
 boolValue

    A more readable and convenient way to access these values in Swift is through Swift's subscript notation:

      let 
  
 remoteConfig 
  
 = 
  
 RemoteConfig 
 . 
 remoteConfig 
 () 
 // Retrieve a string parameter value 
 let 
  
 welcomeMessage 
  
 = 
  
 remoteConfig 
 [ 
 "welcome_message" 
 ]. 
 stringValue 
 // Retrieve a boolean parameter value 
 let 
  
 isFeatureEnabled 
  
 = 
  
 remoteConfig 
 [ 
 "new_feature_flag" 
 ]. 
 boolValue 
 // Retrieve a number parameter value 
 let 
  
 maxItemCount 
  
 = 
  
 remoteConfig 
 [ 
 "max_items" 
 ]. 
 numberValue 
 . 
 intValue

    Use Codable for type-safe configuration

    For more complex configurations, you can use Swift's Codable protocol to decode structured data from Remote Config . This provides type-safe configuration management and simplifies working with complex objects.

      // Define a Codable struct for your configuration 
 struct 
  
 AppFeatureConfig 
 : 
  
 Codable 
  
 { 
  
 let 
  
 isNewFeatureEnabled 
 : 
  
 Bool 
  
 let 
  
 maxUploadSize 
 : 
  
 Int 
  
 let 
  
 themeColors 
 : 
  
 [ 
 String 
 : 
  
 String 
 ] 
 } 
 // Fetch and decode the configuration 
 func 
  
 configureAppFeatures 
 () 
  
 { 
  
 let 
  
 remoteConfig 
  
 = 
  
 RemoteConfig 
 . 
 remoteConfig 
 () 
  
 remoteConfig 
 . 
 fetchAndActivate 
  
 { 
  
 status 
 , 
  
 error 
  
 in 
  
 guard 
  
 error 
  
 == 
  
 nil 
  
 else 
  
 { 
  
 return 
  
 } 
  
 do 
  
 { 
  
 let 
  
 featureConfig 
  
 = 
  
 try 
  
 remoteConfig 
 [ 
 "app_feature_config" 
 ]. 
 decoded 
 ( 
 asType 
 : 
  
 AppFeatureConfig 
 . 
 self 
 ) 
  
 configureApp 
 ( 
 with 
 : 
  
 featureConfig 
 ) 
  
 } 
  
 catch 
  
 { 
  
 // Handle decoding errors 
  
 print 
 ( 
 "Failed to decode configuration: 
 \( 
 error 
 ) 
 " 
 ) 
  
 } 
  
 } 
 }

    This method lets you:

    • Define complex configuration structures.
    • Automatically parse JSON configurations.
    • Ensure type safety when accessing Remote Config values.
    • Provide clean, readable code for handling structured Remote Config templates.

    Use Property Wrappers for declarative configuration in SwiftUI

    Property wrappers are a powerful Swift feature that lets you add custom behavior to property declarations. In SwiftUI, property wrappers are used to manage state, bindings, and other property behaviors. For more information, see the Swift Language Guide .

      struct 
  
 ContentView 
 : 
  
 View 
  
 { 
  
 @ 
 RemoteConfigProperty 
 ( 
 key 
 : 
  
 "cardColor" 
 , 
  
 fallback 
 : 
  
 "#f05138" 
 ) 
  
 var 
  
 cardColor 
  
 var 
  
 body 
 : 
  
 some 
  
 View 
  
 { 
  
 VStack 
  
 { 
  
 Text 
 ( 
 "Dynamic Configuration" 
 ) 
  
 . 
 background 
 ( 
 Color 
 ( 
 hex 
 : 
  
 cardColor 
 )) 
  
 } 
  
 . 
 onAppear 
  
 { 
  
 RemoteConfig 
 . 
 remoteConfig 
 (). 
 fetchAndActivate 
 () 
  
 } 
  
 } 
 }

    Use the @RemoteConfigProperty property wrapper when you want a declarative way to access Remote Config values in SwiftUI, with built-in support for default values and simplified configuration management.

    Step 4: Set parameter values

    Using the Firebase console or the Remote Config backend APIs , you can create new backend default values that override the in-app values according to your desired conditional logic or user targeting. This section walks you through the Firebase console steps to create these values.

    1. In the Firebase console , open your project.
    2. Select Remote Config from the menu to view the Remote Config dashboard.
    3. Define parameters with the same names as the parameters that you defined in your app. For each parameter, you can set a default value (which will eventually override the in-app default value) and you can also set conditional values. To learn more, see Remote Config Parameters and Conditions .

    4. If using custom signal conditions , define the attributes and their values. The following examples show how to define a custom signal condition.

      Swift

        
 Task 
  
 { 
  
 let 
  
 customSignals 
 : 
  
 [ 
 String 
 : 
  
 CustomSignalValue 
 ?] 
  
 = 
  
 [ 
  
 "city" 
 : 
  
 . 
 string 
 ( 
 "Tokyo" 
 ), 
  
 "preferred_event_category" 
 : 
  
 . 
 string 
 ( 
 "sports" 
 ) 
  
 ] 
  
 do 
  
 { 
  
 try 
  
 await 
  
 remoteConfig 
 . 
 setCustomSignals 
 ( 
 customSignals 
 ) 
  
 print 
 ( 
 "Custom signals set successfully!" 
 ) 
  
 } 
  
 catch 
  
 { 
  
 print 
 ( 
 "Error setting custom signals: 
 \( 
 error 
 ) 
 " 
 ) 
  
 } 
 }

      Objective-C

        
 dispatch_async 
 ( 
 dispatch_get_global_queue 
 ( 
 DISPATCH_QUEUE_PRIORITY_DEFAULT 
 , 
  
 0 
 ), 
  
 ^ 
 { 
  
 NSDictionary 
  
 * 
 customSignals 
  
 = 
  
 @{ 
  
 @"city" 
 : 
  
 @"Tokyo" 
 , 
  
 @"preferred_event_category" 
 : 
  
 @"sports" 
  
 } 
 ; 
  
 [ 
 self 
 . 
 remoteConfig 
  
 setCustomSignals 
 : 
 customSignals 
  
 withCompletion 
 :^ 
 ( 
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 error 
 ) 
  
 { 
  
 NSLog 
 ( 
 @"Error setting custom signals: %@" 
 , 
  
 error 
 ); 
  
 } 
  
 else 
  
 { 
  
 NSLog 
 ( 
 @"Custom signals set successfully!" 
 ); 
  
 } 
  
 }]; 
 });

    Step 5: Fetch and activate values

    To fetch parameter values from Remote Config , call the fetchWithCompletionHandler: or fetchWithExpirationDuration:completionHandler: method. Any values that you set on the backend are fetched and cached in the Remote Config object.

    For cases where you want to fetch and activate values in one call, use fetchAndActivateWithCompletionHandler: .

    This example fetches values from the Remote Config backend (not cached values) and calls activateWithCompletionHandler: to make them available to the app:

    Swift

     remoteConfig 
 . 
 fetch 
  
 { 
  
 ( 
 status 
 , 
  
 error 
 ) 
  
 - 
>  
 Void 
  
 in 
  
 if 
  
 status 
  
 == 
  
 . 
 success 
  
 { 
  
 print 
 ( 
 "Config fetched!" 
 ) 
  
 self 
 . 
 remoteConfig 
 . 
 activate 
  
 { 
  
 changed 
 , 
  
 error 
  
 in 
  
 // ... 
  
 } 
  
 } 
  
 else 
  
 { 
  
 print 
 ( 
 "Config not fetched" 
 ) 
  
 print 
 ( 
 "Error: 
 \( 
 error 
 ?. 
 localizedDescription 
  
 ?? 
  
 "No error available." 
 ) 
 " 
 ) 
  
 } 
  
 self 
 . 
 displayWelcome 
 () 
 } 
 
      ViewController 
 . 
 swift

    Objective-C

     [ 
 self 
 . 
 remoteConfig 
  
 fetchWithCompletionHandler 
 :^ 
 ( 
 FIRRemoteConfigFetchStatus 
  
 status 
 , 
  
 NSError 
  
 * 
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 status 
  
 == 
  
 FIRRemoteConfigFetchStatusSuccess 
 ) 
  
 { 
  
 NSLog 
 ( 
 @"Config fetched!" 
 ); 
  
 [ 
 self 
 . 
 remoteConfig 
  
 activateWithCompletion 
 :^ 
 ( 
 BOOL 
  
 changed 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 error 
  
 != 
  
 nil 
 ) 
  
 { 
  
 NSLog 
 ( 
 @"Activate error: %@" 
 , 
  
 error 
 . 
 localizedDescription 
 ); 
  
 } 
  
 else 
  
 { 
  
 dispatch_async 
 ( 
 dispatch_get_main_queue 
 (), 
  
 ^ 
 { 
  
 [ 
 self 
  
 displayWelcome 
 ]; 
  
 }); 
  
 } 
  
 }]; 
  
 } 
  
 else 
  
 { 
  
 NSLog 
 ( 
 @"Config not fetched" 
 ); 
  
 NSLog 
 ( 
 @"Error %@" 
 , 
  
 error 
 . 
 localizedDescription 
 ); 
  
 } 
 }]; 
 
      ViewController 
 . 
 m

    Because these updated parameter values affect the behavior and appearance of your app, you should activate the fetched values at a time that ensures a smooth experience for your user, such as the next time that the user opens your app. See Remote Config loading strategies for more information and examples.

    Step 6: Listen for updates in real time

    After you fetch parameter values, you can use real-time Remote Config to listen for updates from the Remote Config backend. Real-time Remote Config signals to connected devices when updates are available and automatically fetches the changes after you publish a new Remote Config version.

    Real-time updates are supported by the Firebase SDK for Apple platforms v10.7.0+ and higher.

    1. In your app, call addOnConfigUpdateListener to start listening for updates and automatically fetch any new or updated parameter values. The following example listens for updates and when activateWithCompletionHandler is called, uses the newly fetched values to display an updated welcome message.

      Swift

       remoteConfig 
 . 
 addOnConfigUpdateListener 
  
 { 
  
 configUpdate 
 , 
  
 error 
  
 in 
  
 guard 
  
 let 
  
 configUpdate 
 , 
  
 error 
  
 == 
  
 nil 
  
 else 
  
 { 
  
 print 
 ( 
 "Error listening for config updates: 
 \( 
 error 
 ) 
 " 
 ) 
  
 } 
  
 print 
 ( 
 "Updated keys: 
 \( 
 configUpdate 
 . 
 updatedKeys 
 ) 
 " 
 ) 
  
 self 
 . 
 remoteConfig 
 . 
 activate 
  
 { 
  
 changed 
 , 
  
 error 
  
 in 
  
 guard 
  
 error 
  
 == 
  
 nil 
  
 else 
  
 { 
  
 return 
  
 self 
 . 
 displayError 
 ( 
 error 
 ) 
  
 } 
  
 DispatchQueue 
 . 
 main 
 . 
 async 
  
 { 
  
 self 
 . 
 displayWelcome 
 () 
  
 } 
  
 } 
 }

      Objective-C

       __weak 
  
 __typeof__ 
 ( 
 self 
 ) 
  
 weakSelf 
  
 = 
  
 self 
 ; 
 [ 
 self 
 . 
 remoteConfig 
  
 addOnConfigUpdateListener 
 :^ 
 ( 
 FIRRemoteConfigUpdate 
  
 * 
  
 _Nonnull 
  
 configUpdate 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 error 
  
 != 
  
 nil 
 ) 
  
 { 
  
 NSLog 
 ( 
 @"Error listening for config updates %@" 
 , 
  
 error 
 . 
 localizedDescription 
 ); 
  
 } 
  
 else 
  
 { 
  
 NSLog 
 ( 
 @"Updated keys: %@" 
 , 
  
 configUpdate 
 . 
 updatedKeys 
 ); 
  
 __typeof__ 
 ( 
 self 
 ) 
  
 strongSelf 
  
 = 
  
 weakSelf 
 ; 
  
 [ 
 strongSelf 
 . 
 remoteConfig 
  
 activateWithCompletion 
 :^ 
 ( 
 BOOL 
  
 changed 
 , 
  
 NSError 
  
 * 
  
 _Nullable 
  
 error 
 ) 
  
 { 
  
 if 
  
 ( 
 error 
  
 != 
  
 nil 
 ) 
  
 { 
  
 NSLog 
 ( 
 @"Activate error %@" 
 , 
  
 error 
 . 
 localizedDescription 
 ); 
  
 } 
  
 dispatch_async 
 ( 
 dispatch_get_main_queue 
 (), 
  
 ^ 
 { 
  
 [ 
 strongSelf 
  
 displayWelcome 
 ]; 
  
 }); 
  
 }]; 
  
 } 
 }];

    2. The next time you publish a new version of your Remote Config , devices that are running your app and listening for changes will call the completion handler.

    Throttling

    If an app fetches too many times in a short time period, fetch calls are throttled and the SDK returns FIRRemoteConfigFetchStatusThrottled . Before SDK version 6.3.0, the limit was 5 fetch requests in a 60 minute window (newer versions have more permissive limits).

    During app development,you might want to fetch more often to refresh the cache very frequently (many times per hour) to let you rapidly iterate as you develop and test your app. Real-time Remote Config updates automatically bypass the cache when the config is updated on the server. To accommodate rapid iteration on a project with numerous developers, you can temporarily add a FIRRemoteConfigSettings property with a low minimum fetch interval ( MinimumFetchInterval ) in your app.

    The default and recommended production fetch interval for Remote Config is 12 hours, which means that configs won't be fetched from the backend more than once in a 12 hour window, regardless of how many fetch calls are actually made. Specifically, the minimum fetch interval is determined in this following order:

    1. The parameter in fetch(long)
    2. The parameter in FIRRemoteConfigSettings.MinimumFetchInterval
    3. The default value of 12 hours

    Next steps

    If you haven't already, explore the Remote Config use cases , and take a look at some of the key concepts and advanced strategies documentation, including:

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