When the custom event line item is reached in the waterfall mediation chain,
theloadBanner:adConfiguration:completionHandler:method is called on the
class name you provided whencreating a custom
event. In this case,
that method is inSampleCustomEvent, which then calls
theloadBanner:adConfiguration:completionHandler:method inSampleCustomEventBanner.
To request a banner ad, create or modify a class that implementsGADMediationAdapterandloadBanner:adConfiguration:completionHandler:. If a
class that extendsGADMediationAdapteralready exists, implementloadBanner:adConfiguration:completionHandler:there. Additionally, create a
new class to implementGADMediationBannerAd.
In our custom event example,SampleCustomEventimplements
theGADMediationAdapterinterface and then delegates toSampleCustomEventBanner.
Receiving and reporting ad event callbacks to Google Mobile Ads SDK.
The optional parameter defined in the Ad Manager UI is
included in the ad configuration.
The parameter can be accessed throughadConfiguration.credentials.settings[@"parameter"]. This parameter is
typically an ad unit identifier that an ad network SDK requires when
instantiating an ad object.
Whether the ad is successfully fetched or encounters an error, you
would callGADMediationBannerLoadCompletionHandler. In the event of success,
pass through the class that implementsGADMediationBannerAdwith anilvalue
for the error parameter; in the event of failure, pass through the error you
encountered.
Typically, these methods are implemented inside callbacks from the
third-party SDK your adapter implements. For this example, the Sample SDK
has aSampleBannerAdDelegatewith relevant callbacks:
Once you've calledGADMediationBannerLoadCompletionHandlerwith a loaded ad,
the returnedGADMediationBannerAdEventDelegatedelegate object can then be
used by the adapter to forward presentation events from the third-party SDK to
Google Mobile Ads SDK. TheSampleCustomEventBannerclass implements theSampleBannerAdDelegateprotocol to forward callbacks from the sample ad
network to Google Mobile Ads SDK.
It's important that your custom event forwards as many of these callbacks as
possible, so that your app receives these equivalent events from Google Mobile Ads SDK.
Here's an example of using callbacks:
This completes the custom events implementation for banner ads. The full example
is available onGitHub.
You can use it with an ad network that is already supported or modify it to
display custom event banner ads.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eTo request a banner ad within a custom event, create a class that implements \u003ccode\u003eGADMediationAdapter\u003c/code\u003e and the \u003ccode\u003eloadBanner:adConfiguration:completionHandler:\u003c/code\u003e method.\u003c/p\u003e\n"],["\u003cp\u003eA separate class implementing \u003ccode\u003eGADMediationBannerAd\u003c/code\u003e should handle loading the ad, reporting events to the Google Mobile Ads SDK, and providing a \u003ccode\u003eUIView\u003c/code\u003e property for display.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGADMediationBannerLoadCompletionHandler\u003c/code\u003e is called upon ad load success or failure, passing the \u003ccode\u003eGADMediationBannerAd\u003c/code\u003e instance or an error, respectively.\u003c/p\u003e\n"],["\u003cp\u003eForward relevant ad events (like clicks) from the third-party ad network SDK to the Google Mobile Ads SDK using the \u003ccode\u003eGADMediationBannerAdEventDelegate\u003c/code\u003e received from the \u003ccode\u003eGADMediationBannerLoadCompletionHandler\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the complete custom event example on GitHub for implementation details and guidance.\u003c/p\u003e\n"]]],["To request a banner ad via custom events, implement `GADMediationAdapter` and `loadBanner:adConfiguration:completionHandler:`, delegating to a class that implements `GADMediationBannerAd`. This class is responsible for loading the banner, implementing `GADMediationBannerAd`, and reporting ad event callbacks. The `loadBanner:` method within this class fetches the ad, and then invokes a completion handler (`GADMediationBannerLoadCompletionHandler`) whether loading succeeds or fails, passing the banner ad or an error, respectively. Finally, use `GADMediationBannerAdEventDelegate` to forward presentation events.\n"],null,["Prerequisites\n\nComplete the [custom events setup](/ad-manager/mobile-ads-sdk/ios/custom-events/setup).\n\nRequest a banner ad\n\nWhen the custom event line item is reached in the waterfall mediation chain,\nthe `loadBanner:adConfiguration:completionHandler:` method is called on the\nclass name you provided when [creating a custom\nevent](/ad-manager/mobile-ads-sdk/ios/custom-events/setup#create). In this case,\nthat method is in `SampleCustomEvent`, which then calls\nthe `loadBanner:adConfiguration:completionHandler:` method in\n`SampleCustomEventBanner`.\n\nTo request a banner ad, create or modify a class that implements\n`GADMediationAdapter` and `loadBanner:adConfiguration:completionHandler:`. If a\nclass that extends `GADMediationAdapter` already exists, implement\n`loadBanner:adConfiguration:completionHandler:` there. Additionally, create a\nnew class to implement `GADMediationBannerAd`.\n\nIn our custom event example,\n[`SampleCustomEvent`](//github.com/googleads/googleads-mobile-ios-mediation/blob/main/example/CustomEvent/SampleCustomEvent.m) implements\nthe `GADMediationAdapter` interface and then delegates to\n`SampleCustomEventBanner`. \n\nSwift \n\n```swift\nimport GoogleMobileAds\n\nclass SampleCustomEvent: NSObject, MediationAdapter {\n\n fileprivate var bannerAd: SampleCustomEventBanner?\n ...\n\n func loadBanner(\n for adConfiguration: MediationBannerAdConfiguration,\n completionHandler: @escaping GADMediationBannerLoadCompletionHandler\n ) {\n self.bannerAd = SampleCustomEventBanner()\n self.bannerAd?.loadBanner(\n for: adConfiguration, completionHandler: completionHandler)\n }\n}\n```\n\nObjective-C \n\n```objective-c\n#import \"SampleCustomEvent.h\"\n\n@implementation SampleCustomEvent\n...\n\nSampleCustomEventBanner *sampleBanner;\n\n- (void)loadBannerForAdConfiguration:\n (GADMediationBannerAdConfiguration *)adConfiguration\n completionHandler:(GADMediationBannerLoadCompletionHandler)\n completionHandler {\n sampleBanner = [[SampleCustomEventBanner alloc] init];\n [sampleBanner loadBannerForAdConfiguration:adConfiguration\n completionHandler:completionHandler];\n}\n```\n\n`SampleCustomEventBanner` is responsible for the following tasks:\n\n- Loading the banner ad and invoking a\n [`GADMediationBannerLoadCompletionHandler`](/ad-manager/mobile-ads-sdk/ios/api/reference/Protocols/GADMediationAdapter) method once\n loading completes.\n\n- Implementing the `GADMediationBannerAd` protocol.\n\n- Receiving and reporting ad event callbacks to Google Mobile Ads SDK.\n\nThe optional parameter defined in the Ad Manager UI is\nincluded in the ad configuration.\nThe parameter can be accessed through\n`adConfiguration.credentials.settings[@\"parameter\"]`. This parameter is\ntypically an ad unit identifier that an ad network SDK requires when\ninstantiating an ad object. \n\nSwift \n\n```swift\nclass SampleCustomEventBanner: NSObject, MediationBannerAd {\n /// The Sample Ad Network banner ad.\n var bannerAd: SampleBanner?\n\n /// The ad event delegate to forward ad rendering events to Google Mobile Ads SDK.\n var delegate: MediationBannerAdEventDelegate?\n\n /// Completion handler called after ad load\n var completionHandler: GADMediationBannerLoadCompletionHandler?\n\n func loadBanner(\n for adConfiguration: MediationBannerAdConfiguration,\n completionHandler: @escaping GADMediationBannerLoadCompletionHandler\n ) {\n // Create the bannerView with the appropriate size.\n let adSize = adConfiguration.adSize\n bannerAd = SampleBanner(\n frame: CGRect(x: 0, y: 0, width: adSize.size.width, height: adSize.size.height))\n bannerAd?.delegate = self\n bannerAd?.adUnit = adConfiguration.credentials.settings[\"parameter\"] as? String\n let adRequest = SampleAdRequest()\n adRequest.testMode = adConfiguration.isTestRequest\n self.completionHandler = completionHandler\n bannerAd?.fetchAd(adRequest)\n }\n}\n```\n\nObjective-C \n\n```objective-c\n#import \"SampleCustomEventBanner.h\"\n\n@interface SampleCustomEventBanner () \u003cSampleBannerAdDelegate,\n GADMediationBannerAd\u003e {\n /// The sample banner ad.\n SampleBanner *_bannerAd;\n\n /// The completion handler to call when the ad loading succeeds or fails.\n GADMediationBannerLoadCompletionHandler _loadCompletionHandler;\n\n /// The ad event delegate to forward ad rendering events to the Google Mobile\n /// Ads SDK.\n id \u003cGADMediationBannerAdEventDelegate\u003e _adEventDelegate;\n}\n@end\n\n@implementation SampleCustomEventBanner\n\n- (void)loadBannerForAdConfiguration:\n (GADMediationBannerAdConfiguration *)adConfiguration\n completionHandler:(GADMediationBannerLoadCompletionHandler)\n completionHandler {\n __block atomic_flag completionHandlerCalled = ATOMIC_FLAG_INIT;\n __block GADMediationBannerLoadCompletionHandler originalCompletionHandler =\n [completionHandler copy];\n\n _loadCompletionHandler = ^id\u003cGADMediationBannerAdEventDelegate\u003e(\n _Nullable id\u003cGADMediationBannerAd\u003e ad, NSError *_Nullable error) {\n // Only allow completion handler to be called once.\n if (atomic_flag_test_and_set(&completionHandlerCalled)) {\n return nil;\n }\n\n id\u003cGADMediationBannerAdEventDelegate\u003e delegate = nil;\n if (originalCompletionHandler) {\n // Call original handler and hold on to its return value.\n delegate = originalCompletionHandler(ad, error);\n }\n\n // Release reference to handler. Objects retained by the handler will also\n // be released.\n originalCompletionHandler = nil;\n\n return delegate;\n };\n\n NSString *adUnit = adConfiguration.credentials.settings[@\"parameter\"];\n _bannerAd = [[SampleBanner alloc]\n initWithFrame:CGRectMake(0, 0, adConfiguration.adSize.size.width,\n adConfiguration.adSize.size.height)];\n _bannerAd.adUnit = adUnit;\n _bannerAd.delegate = self;\n SampleAdRequest *adRequest = [[SampleAdRequest alloc] init];\n adRequest.testMode = adConfiguration.isTestRequest;\n [_bannerAd fetchAd:adRequest];\n}\n```\n\nWhether the ad is successfully fetched or encounters an error, you\nwould call `GADMediationBannerLoadCompletionHandler`. In the event of success,\npass through the class that implements `GADMediationBannerAd` with a `nil` value\nfor the error parameter; in the event of failure, pass through the error you\nencountered.\n\nTypically, these methods are implemented inside callbacks from the\nthird-party SDK your adapter implements. For this example, the Sample SDK\nhas a `SampleBannerAdDelegate` with relevant callbacks: \n\nSwift \n\n```swift\nfunc bannerDidLoad(_ banner: SampleBanner) {\n if let handler = completionHandler {\n delegate = handler(self, nil)\n }\n}\n\nfunc banner(\n _ banner: SampleBanner, didFailToLoadAdWith errorCode: SampleErrorCode\n) {\n let error =\n SampleCustomEventUtilsSwift.SampleCustomEventErrorWithCodeAndDescription(\n code: SampleCustomEventErrorCodeSwift\n .SampleCustomEventErrorAdLoadFailureCallback,\n description:\n \"Sample SDK returned an ad load failure callback with error code: \\(errorCode)\"\n )\n if let handler = completionHandler {\n delegate = handler(nil, error)\n }\n}\n```\n\nObjective-C \n\n```objective-c\n- (void)bannerDidLoad:(SampleBanner *)banner {\n _adEventDelegate = _loadCompletionHandler(self, nil);\n}\n\n- (void)banner:(SampleBanner *)banner\n didFailToLoadAdWithErrorCode:(SampleErrorCode)errorCode {\n NSError *error = SampleCustomEventErrorWithCodeAndDescription(\n SampleCustomEventErrorAdLoadFailureCallback,\n [NSString stringWithFormat:@\"Sample SDK returned an ad load failure \"\n @\"callback with error code: %@\",\n errorCode]);\n _adEventDelegate = _loadCompletionHandler(nil, error);\n}\n```\n\n`GADMediationBannerAd` requires implementing a `UIView` property: \n\nSwift \n\n```swift\nvar view: UIView {\n return bannerAd ?? UIView()\n}\n```\n\nObjective-C \n\n```objective-c\n- (nonnull UIView *)view {\n return _bannerAd;\n}\n```\n\nForward mediation events to Google Mobile Ads SDK\n\nOnce you've called `GADMediationBannerLoadCompletionHandler` with a loaded ad,\nthe returned `GADMediationBannerAdEventDelegate` delegate object can then be\nused by the adapter to forward presentation events from the third-party SDK to\nGoogle Mobile Ads SDK. The `SampleCustomEventBanner` class implements the\n`SampleBannerAdDelegate` protocol to forward callbacks from the sample ad\nnetwork to Google Mobile Ads SDK.\n\nIt's important that your custom event forwards as many of these callbacks as\npossible, so that your app receives these equivalent events from Google Mobile Ads SDK.\nHere's an example of using callbacks: \n\nSwift \n\n```swift\nfunc bannerWillLeaveApplication(_ banner: SampleBanner) {\n delegate?.reportClick()\n}\n```\n\nObjective-C \n\n```objective-c\n- (void)bannerWillLeaveApplication:(SampleBanner *)banner {\n [_adEventDelegate reportClick];\n}\n```\n\nThis completes the custom events implementation for banner ads. The full example\nis available on\n[GitHub](//github.com/googleads/googleads-mobile-ios-mediation/tree/main/example/CustomEvent).\nYou can use it with an ad network that is already supported or modify it to\ndisplay custom event banner ads."]]
