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原生广告自定义事件

前提条件

请求原生广告

在达到广告瀑布流中介链内的自定义事件订单项时，系统会对您在创建自定义事件时提供的类名称调用 loadNativeAd:adConfiguration:completionHandler: 方法。在这种情况下，该方法位于 SampleCustomEvent 中，后者随后会调用 SampleCustomEventNative 中的 loadNativeAd:adConfiguration:completionHandler: 方法。

若要请求原生广告，请创建或修改实现 GADMediationAdapter 和 loadNativeAd:adConfiguration:completionHandler: 的类。如果扩展 GADMediationAdapter 的类已存在，请在该类中实现 loadNativeAd:adConfiguration:completionHandler:。此外，请创建一个新类来实现 GADMediationNativeAd。

在我们的自定义事件示例中，SampleCustomEvent 会实现 GADMediationAdapter 接口，然后委托给 SampleCustomEventNative。

Swift

import GoogleMobileAds

class SampleCustomEvent: NSObject, GADMediationAdapter {

  fileprivate var nativeAd: SampleCustomEventNativeAd?

  func loadNativeAd(
    for adConfiguration: GADMediationNativeAdConfiguration,
    completionHandler: @escaping GADMediationNativeAdLoadCompletionHandler
  ) {
    self.nativeAd = SampleCustomEventNativeAd()
    self.nativeAd?.loadNativeAd(
      for: adConfiguration, completionHandler: completionHandler)
  }
}

Objective-C

#import "SampleCustomEvent.h"

@implementation SampleCustomEvent

SampleCustomEventNativeAd *sampleNativeAd;

- (void)loadNativeAdForAdConfiguration:
            (GADMediationNativeAdConfiguration *)adConfiguration
                     completionHandler:
                         (GADMediationNativeAdLoadCompletionHandler)
                             completionHandler {
  sampleNative = [[SampleCustomEventNativeAd alloc] init];
  [sampleNative loadNativeAdForAdConfiguration:adConfiguration
                             completionHandler:completionHandler];
}

SampleCustomEventNative` 负责执行以下任务：

加载原生广告
实现 GADMediationNativeAd 协议。
接收广告事件回调并将其报告给 Google 移动广告 SDK

Ad Manager 界面中定义的可选参数包含在广告配置中。此参数可通过 adConfiguration.credentials.settings[@"parameter"] 进行访问。通常，此参数是实例化广告对象时广告联盟 SDK 所需的广告单元标识符。

Swift

class SampleCustomEventNativeAd: NSObject, GADMediationNativeAd {
  /// The Sample Ad Network native ad.
  var nativeAd: SampleNativeAd?

  /// The ad event delegate to forward ad rendering events to the Google Mobile
  /// Ads SDK.
  var delegate: GADMediationNativeAdEventDelegate?

  /// Completion handler called after ad load
  var completionHandler: GADMediationNativeLoadCompletionHandler?

  func loadNativeAd(
    for adConfiguration: GADMediationNativeAdConfiguration,
    completionHandler: @escaping GADMediationNativeLoadCompletionHandler
  ) {
    let adLoader = SampleNativeAdLoader()
    let sampleRequest = SampleNativeAdRequest()

    // The Google Mobile Ads SDK requires the image assets to be downloaded
    // automatically unless the publisher specifies otherwise by using the
    // GADNativeAdImageAdLoaderOptions object's disableImageLoading property. If
    // your network doesn't have an option like this and instead only ever
    // returns URLs for images (rather than the images themselves), your adapter
    // should download image assets on behalf of the publisher. This should be
    // done after receiving the native ad object from your network's SDK, and
    // before calling the connector's adapter:didReceiveMediatedNativeAd: method.
    sampleRequest.shouldDownloadImages = true
    sampleRequest.preferredImageOrientation = NativeAdImageOrientation.any
    sampleRequest.shouldRequestMultipleImages = false
    let options = adConfiguration.options
    for loaderOptions: GADAdLoaderOptions in options {
      if let imageOptions = loaderOptions as? GADNativeAdImageAdLoaderOptions {
        sampleRequest.shouldRequestMultipleImages =
          imageOptions.shouldRequestMultipleImages
        // If the GADNativeAdImageAdLoaderOptions' disableImageLoading property is
        // YES, the adapter should send just the URLs for the images.
        sampleRequest.shouldDownloadImages = !imageOptions.disableImageLoading
      } else if let mediaOptions = loaderOptions
        as? GADNativeAdMediaAdLoaderOptions
      {
        switch mediaOptions.mediaAspectRatio {
        case GADMediaAspectRatio.landscape:
          sampleRequest.preferredImageOrientation =
            NativeAdImageOrientation.landscape
        case GADMediaAspectRatio.portrait:
          sampleRequest.preferredImageOrientation =
            NativeAdImageOrientation.portrait
        default:
          sampleRequest.preferredImageOrientation = NativeAdImageOrientation.any
        }
      }
    }
    // This custom event uses the server parameter to carry an ad unit ID, which
    // is the most common use case.
    adLoader.delegate = self
    adLoader.adUnitID =
      adConfiguration.credentials.settings["parameter"] as? String
    self.completionHandler = completionHandler
    adLoader.fetchAd(sampleRequest)
  }
}

Objective-C

#import "SampleCustomEventNativeAd.h"

@interface SampleCustomEventNativeAd () <SampleNativeAdDelegate,
                                         GADMediationNativeAd> {
  /// The sample native ad.
  SampleNativeAd *_nativeAd;

  /// The completion handler to call when the ad loading succeeds or fails.
  GADMediationNativeLoadCompletionHandler _loadCompletionHandler;

  /// The ad event delegate to forward ad rendering events to the Google Mobile
  /// Ads SDK.
  id<GADMediationNativeAdEventDelegate> _adEventDelegate;
}
@end

- (void)loadNativeAdForAdConfiguration:
            (GADMediationNativeAdConfiguration *)adConfiguration
                     completionHandler:(GADMediationNativeLoadCompletionHandler)
                                           completionHandler {
  __block atomic_flag completionHandlerCalled = ATOMIC_FLAG_INIT;
  __block GADMediationNativeLoadCompletionHandler originalCompletionHandler =
      [completionHandler copy];

  _loadCompletionHandler = ^id<GADMediationNativeAdEventDelegate>(
      _Nullable id<GADMediationNativeAd> ad, NSError *_Nullable error) {
    // Only allow completion handler to be called once.
    if (atomic_flag_test_and_set(&completionHandlerCalled)) {
      return nil;
    }

    id<GADMediationNativeAdEventDelegate> delegate = nil;
    if (originalCompletionHandler) {
      // Call original handler and hold on to its return value.
      delegate = originalCompletionHandler(ad, error);
    }

    // Release reference to handler. Objects retained by the handler will also
    // be released.
    originalCompletionHandler = nil;

    return delegate;
  };

  SampleNativeAdLoader *adLoader = [[SampleNativeAdLoader alloc] init];
  SampleNativeAdRequest *sampleRequest = [[SampleNativeAdRequest alloc] init];

  // The Google Mobile Ads SDK requires the image assets to be downloaded
  // automatically unless the publisher specifies otherwise by using the
  // GADNativeAdImageAdLoaderOptions object's disableImageLoading property. If
  // your network doesn't have an option like this and instead only ever returns
  // URLs for images (rather than the images themselves), your adapter should
  // download image assets on behalf of the publisher. This should be done after
  // receiving the native ad object from your network's SDK, and before calling
  // the connector's adapter:didReceiveMediatedNativeAd: method.
  sampleRequest.shouldDownloadImages = YES;

  sampleRequest.preferredImageOrientation = NativeAdImageOrientationAny;
  sampleRequest.shouldRequestMultipleImages = NO;
  sampleRequest.testMode = adConfiguration.isTestRequest;

  for (GADAdLoaderOptions *loaderOptions in adConfiguration.options) {
    if ([loaderOptions isKindOfClass:[GADNativeAdImageAdLoaderOptions class]]) {
      GADNativeAdImageAdLoaderOptions *imageOptions =
          (GADNativeAdImageAdLoaderOptions *)loaderOptions;
      sampleRequest.shouldRequestMultipleImages =
          imageOptions.shouldRequestMultipleImages;

      // If the GADNativeAdImageAdLoaderOptions' disableImageLoading property is
      // YES, the adapter should send just the URLs for the images.
      sampleRequest.shouldDownloadImages = !imageOptions.disableImageLoading;
    } else if ([loaderOptions
                   isKindOfClass:[GADNativeAdMediaAdLoaderOptions class]]) {
      GADNativeAdMediaAdLoaderOptions *mediaOptions =
          (GADNativeAdMediaAdLoaderOptions *)loaderOptions;
      switch (mediaOptions.mediaAspectRatio) {
        case GADMediaAspectRatioLandscape:
          sampleRequest.preferredImageOrientation =
              NativeAdImageOrientationLandscape;
          break;
        case GADMediaAspectRatioPortrait:
          sampleRequest.preferredImageOrientation =
              NativeAdImageOrientationPortrait;
          break;
        default:
          sampleRequest.preferredImageOrientation = NativeAdImageOrientationAny;
          break;
      }
    } else if ([loaderOptions isKindOfClass:[GADNativeAdViewAdOptions class]]) {
      _nativeAdViewAdOptions = (GADNativeAdViewAdOptions *)loaderOptions;
    }
  }

  // This custom event uses the server parameter to carry an ad unit ID, which
  // is the most common use case.
  NSString *adUnit = adConfiguration.credentials.settings[@"parameter"];
  adLoader.adUnitID = adUnit;
  adLoader.delegate = self;

  [adLoader fetchAd:sampleRequest];
}

无论广告是已成功提取还是遇到错误，您都需要调用 GADMediationNativeAdLoadCompletionHandler。如果成功，请传递实现 GADMediationNativeAd 的类，其中错误参数的值为 nil；如果失败，请传递您遇到的错误。

通常，这些方法是在您的适配器所实现的第三方 SDK 的回调中实现的。在此示例中，示例 SDK 具有一个 SampleNativeAdDelegate 及相关回调：

Swift

func adLoader(
  _ adLoader: SampleNativeAdLoader, didReceive nativeAd: SampleNativeAd
) {
  extraAssets = [
    SampleCustomEventConstantsSwift.awesomenessKey: nativeAd.degreeOfAwesomeness
      ?? ""
  ]

  if let image = nativeAd.image {
    images = [GADNativeAdImage(image: image)]
  } else {
    let imageUrl = URL(fileURLWithPath: nativeAd.imageURL)
    images = [GADNativeAdImage(url: imageUrl, scale: nativeAd.imageScale)]
  }
  if let mappedIcon = nativeAd.icon {
    icon = GADNativeAdImage(image: mappedIcon)
  } else {
    let iconURL = URL(fileURLWithPath: nativeAd.iconURL)
    icon = GADNativeAdImage(url: iconURL, scale: nativeAd.iconScale)
  }

  adChoicesView = SampleAdInfoView()
  self.nativeAd = nativeAd
  if let handler = completionHandler {
    delegate = handler(self, nil)
  }
}

func adLoader(
  _ adLoader: SampleNativeAdLoader,
  didFailToLoadAdWith errorCode: SampleErrorCode
) {
  let error =
    SampleCustomEventUtilsSwift.SampleCustomEventErrorWithCodeAndDescription(
      code: SampleCustomEventErrorCodeSwift
        .SampleCustomEventErrorAdLoadFailureCallback,
      description:
        "Sample SDK returned an ad load failure callback with error code: \(errorCode)"
    )
  if let handler = completionHandler {
    delegate = handler(nil, error)
  }
}

Objective-C

- (void)adLoader:(SampleNativeAdLoader *)adLoader
    didReceiveNativeAd:(SampleNativeAd *)nativeAd {
  if (nativeAd.image) {
    _images = @[ [[GADNativeAdImage alloc] initWithImage:nativeAd.image] ];
  } else {
    NSURL *imageURL = [[NSURL alloc] initFileURLWithPath:nativeAd.imageURL];
    _images = @[ [[GADNativeAdImage alloc] initWithURL:imageURL
                                                 scale:nativeAd.imageScale] ];
  }

  if (nativeAd.icon) {
    _icon = [[GADNativeAdImage alloc] initWithImage:nativeAd.icon];
  } else {
    NSURL *iconURL = [[NSURL alloc] initFileURLWithPath:nativeAd.iconURL];
    _icon = [[GADNativeAdImage alloc] initWithURL:iconURL
                                            scale:nativeAd.iconScale];
  }

  // The sample SDK provides an AdChoices view (SampleAdInfoView). If your SDK
  // provides image and click through URLs for its AdChoices icon instead of an
  // actual UIView, the adapter is responsible for downloading the icon image
  // and creating the AdChoices icon view.
  _adChoicesView = [[SampleAdInfoView alloc] init];
  _nativeAd = nativeAd;

  _adEventDelegate = _loadCompletionHandler(self, nil);
}

- (void)adLoader:(SampleNativeAdLoader *)adLoader
    didFailToLoadAdWithErrorCode:(SampleErrorCode)errorCode {
  NSError *error = SampleCustomEventErrorWithCodeAndDescription(
      SampleCustomEventErrorAdLoadFailureCallback,
      [NSString stringWithFormat:@"Sample SDK returned an ad load failure "
                                 @"callback with error code: %@",
                                 errorCode]);
  _adEventDelegate = _loadCompletionHandler(nil, error);
}

映射原生广告

对于原生广告，不同的 SDK 都有自己独特的广告格式。例如，一个 SDK 可能返回包含“title”字段的对象，而另一个 SDK 返回的对象可能包含“headline”字段。此外，用于跟踪展示和处理点击的方法也可能会因 SDK 而异。

为了解决这些问题，当自定义事件从其参与中介的 SDK 收到原生广告对象时，应使用实现 GADMediationNativeAd 的类（如 SampleCustomEventNativeAd）来“映射”参与中介的 SDK 的原生广告对象，以便其与 Google 移动广告 SDK 预期的接口相匹配。

现在，我们来详细了解一下 SampleCustomEventNativeAd 的实现详情。

存储您的映射

GADMediationNativeAd 应实现从其他 SDK 的属性映射到的特定属性：

Swift

var nativeAd: SampleNativeAd?

var headline: String? {
  return nativeAd?.headline
}

var images: [GADNativeAdImage]?

var body: String? {
  return nativeAd?.body
}

var icon: GADNativeAdImage?

var callToAction: String? {
  return nativeAd?.callToAction
}

var starRating: NSDecimalNumber? {
  return nativeAd?.starRating
}

var store: String? {
  return nativeAd?.store
}

var price: String? {
  return nativeAd?.price
}

var advertiser: String? {
  return nativeAd?.advertiser
}

var extraAssets: [String: Any]? {
  return [
    SampleCustomEventConstantsSwift.awesomenessKey:
      nativeAd?.degreeOfAwesomeness
      ?? ""
  ]
}

var adChoicesView: UIView?

var mediaView: UIView? {
  return nativeAd?.mediaView
}

Objective-C

/// Used to store the ad's images. In order to implement the
/// GADMediationNativeAd protocol, we use this class to return the images
/// property.
NSArray<GADNativeAdImage *> *_images;

/// Used to store the ad's icon. In order to implement the GADMediationNativeAd
/// protocol, we use this class to return the icon property.
GADNativeAdImage *_icon;

/// Used to store the ad's ad choices view. In order to implement the
/// GADMediationNativeAd protocol, we use this class to return the adChoicesView
/// property.
UIView *_adChoicesView;

- (nullable NSString *)headline {
  return _nativeAd.headline;
}

- (nullable NSArray<GADNativeAdImage *> *)images {
  return _images;
}

- (nullable NSString *)body {
  return _nativeAd.body;
}

- (nullable GADNativeAdImage *)icon {
  return _icon;
}

- (nullable NSString *)callToAction {
  return _nativeAd.callToAction;
}

- (nullable NSDecimalNumber *)starRating {
  return _nativeAd.starRating;
}

- (nullable NSString *)store {
  return _nativeAd.store;
}

- (nullable NSString *)price {
  return _nativeAd.price;
}

- (nullable NSString *)advertiser {
  return _nativeAd.advertiser;
}

- (nullable NSDictionary<NSString *, id> *)extraAssets {
  return
      @{SampleCustomEventExtraKeyAwesomeness : _nativeAd.degreeOfAwesomeness};
}

- (nullable UIView *)adChoicesView {
  return _adChoicesView;
}

- (nullable UIView *)mediaView {
  return _nativeAd.mediaView;
}

- (BOOL)hasVideoContent {
  return self.mediaView != nil;
}

除了那些由 Google 移动广告 SDK 定义的素材资源之外，一些参与中介的广告联盟还可以提供额外的素材资源。GADMediationNativeAd 协议包含一个名为 extraAssets 的方法，Google 移动广告 SDK 使用该方法从您的映射器中检索所有这些“额外”素材资源。

映射图片素材资源

与较为简单的数据类型（如 NSString 或 double）相比，映射图片素材资源会更加复杂。图片既可以自动下载，也可以作为网址值返回，而且其像素密度可能也不尽相同。

为了帮助您管理这些详细信息，Google 移动广告 SDK 提供了 GADNativeAdImage 类。开发者应该使用此类将图片素材资源信息（无论是实际的 UIImage 对象还是只是 NSURL 值）返回给 Google 移动广告 SDK。

下面的代码说明了映射器类如何创建一个 GADNativeAdImage 来保留图标图片：

Swift

if let image = nativeAd.image {
  images = [GADNativeAdImage(image: image)]
} else {
  let imageUrl = URL(fileURLWithPath: nativeAd.imageURL)
  images = [GADNativeAdImage(url: imageUrl, scale: nativeAd.imageScale)]
}

Objective-C

if (nativeAd.image) {
  _images = @[ [[GADNativeAdImage alloc] initWithImage:nativeAd.image] ];
} else {
  NSURL *imageURL = [[NSURL alloc] initFileURLWithPath:nativeAd.imageURL];
  _images = @[ [[GADNativeAdImage alloc] initWithURL:imageURL
                                               scale:nativeAd.imageScale] ];
}

展示和点击事件

Google 移动广告 SDK 和参与中介的 SDK 都需要知道展示或点击发生的时间，但只需要有一个 SDK 跟踪这些事件。有两种不同做法可供自定义事件选用，具体取决于参与中介的 SDK 是否支持自行跟踪展示和点击。

使用 Google 移动广告 SDK 跟踪点击和展示

如果参与中介的 SDK 不自行执行展示和点击跟踪，但提供了记录点击和展示的方法，则 Google 移动广告 SDK 可以跟踪这些事件并通知适配器。GADMediationNativeAd 协议包含 didRecordImpression: 和 didRecordClickOnAssetWithName:view:viewController: 这两个方法，自定义事件可通过实现这两个方法来调用参与中介的原生广告对象中的相应方法：

Swift

func didRecordImpression() {
  nativeAd?.recordImpression()
}

func didRecordClickOnAsset(
  withName assetName: GADUnifiedNativeAssetIdentifier,
  view: UIView,
  wController: UIViewController
) {
  nativeAd?.handleClick(on: view)
}

Objective-C

- (void)didRecordImpression {
  if (self.nativeAd) {
    [self.nativeAd recordImpression];
  }
}

- (void)didRecordClickOnAssetWithName:(GADUnifiedNativeAssetIdentifier)assetName
                                 view:(UIView *)view
                       viewController:(UIViewController *)viewController {
  if (self.nativeAd) {
    [self.nativeAd handleClickOnView:view];
  }
}

由于实现 GADMediationNativeAd 协议的类保留了对示例 SDK 的原生广告对象的引用，因此可调用该对象中的相应方法来报告点击或展示。请注意，didRecordClickOnAssetWithName:view:viewController: 方法仅接受一个参数（即 View 对象），该对象与获得点击的原生广告素材资源相对应。

使用参与中介的 SDK 跟踪点击和展示

一些参与中介的 SDK 可能偏好自行跟踪点击和展示。在这种情况下，您应该实现 handlesUserClicks 和 handlesUserImpressions 方法，如以下代码段所示。通过返回 YES，您可以指明自定义事件会负责跟踪这些事件，并在这些事件发生时通知 Google 移动广告 SDK。

替换点击和展示跟踪方法的自定义事件可以使用 didRenderInView: 消息，将原生广告视图传递给参与中介的 SDK 的原生广告对象，以便参与中介的 SDK 进行实际跟踪。我们自定义事件示例项目（本指南中的代码段均选自这一项目）中的示例 SDK 并没有采用这种做法。但如要采用这种做法，则自定义事件代码会调用 setNativeAdView:view: 方法，如以下代码段所示：

Swift

func handlesUserClicks() -> Bool {
  return true
}
func handlesUserImpressions() -> Bool {
  return true
}

func didRender(
  in view: UIView, clickableAssetViews: [GADNativeAssetIdentifier: UIView],
  nonclickableAssetViews: [GADNativeAssetIdentifier: UIView],
  viewController: UIViewController
) {
  // This method is called when the native ad view is rendered. Here you would pass the UIView
  // back to the mediated network's SDK.
  self.nativeAd?.setNativeAdView(view)
}

Objective-C

- (BOOL)handlesUserClicks {
  return YES;
}

- (BOOL)handlesUserImpressions {
  return YES;
}

- (void)didRenderInView:(UIView *)view
       clickableAssetViews:(NSDictionary<GADNativeAssetIdentifier, UIView *> *)
                               clickableAssetViews
    nonclickableAssetViews:(NSDictionary<GADNativeAssetIdentifier, UIView *> *)
                               nonclickableAssetViews
            viewController:(UIViewController *)viewController {
  // This method is called when the native ad view is rendered. Here you would
  // pass the UIView back to the mediated network's SDK. Playing video using
  // SampleNativeAd's playVideo method
  [_nativeAd setNativeAdView:view];
}

将中介事件转发至 Google 移动广告 SDK

在您调用 GADMediationNativeLoadCompletionHandler 并返回已加载的广告后，适配器便可以使用返回的 GADMediationNativeAdEventDelegate 委托对象，将展示事件从第三方 SDK 转发至 Google 移动广告 SDK。

您的自定义事件必须尽可能多地转发这些回调，以便您的应用从 Google 移动广告 SDK 接收这些等效事件。以下示例展示了如何使用回调：

到这里，我们已经实现针对原生广告的自定义事件。GitHub 上提供了完整的示例。