chore(swift): update docs for appsync events IAM authentication with amplify (#8446)

Author: thisisabhash

src/pages/[platform]/build-a-backend/data/connect-event-api/index.mdx

@@ -346,146 +346,11 @@ let authorizer = AuthTokenAuthorizer(fetchLatestAuthToken: getUserPoolAccessToke
 
 #### AWS IAM
 
-If you are using Amplify Auth, you can use the following class to implement SigV4 signing logic:
-
-```swift
-import Foundation
-import Amplify 
-import AWSPluginsCore 
-import AwsCommonRuntimeKit 
-import AWSSDKHTTPAuth 
-import Smithy 
-import SmithyHTTPAPI
-import SmithyHTTPAuth
-import SmithyHTTPAuthAPI
-import SmithyIdentity
-
-class AppSyncEventsSigner {
-    
-    public static func createAppSyncSigner(region: String) -> ((URLRequest) async throws -> URLRequest) {
-        return { request in
-            try await signAppSyncRequest(request,
-                                         region: region)
-        }
-    }
-    
-    private static var signer = {
-        return AWSSigV4Signer()
-    }()
-    
-    static func signAppSyncRequest(_ urlRequest: URLRequest,
-                                   region: Swift.String,
-                                   signingName: Swift.String = "appsync",
-                                   date: Date = Date()) async throws -> URLRequest {
-        CommonRuntimeKit.initialize()
-        
-        // Convert URLRequest to SDK's HTTPRequest
-        guard let requestBuilder = try createAppSyncSdkHttpRequestBuilder(
-            urlRequest: urlRequest) else {
-            return urlRequest
-        }
-        
-        // Retrieve the credentials from credentials provider
-        let credentials: AWSCredentialIdentity
-        let authSession = try await Amplify.Auth.fetchAuthSession()
-        if let awsCredentialsProvider = authSession as? AuthAWSCredentialsProvider {
-            let awsCredentials = try awsCredentialsProvider.getAWSCredentials().get()
-            credentials = try awsCredentials.toAWSSDKCredentials()
-        } else {
-            let error = AuthError.unknown("Auth session does not include AWS credentials information")
-            throw error
-        }
-        
-        // Prepare signing
-        let flags = SigningFlags(useDoubleURIEncode: true,
-                                 shouldNormalizeURIPath: true,
-                                 omitSessionToken: false)
-        let signedBodyHeader: AWSSignedBodyHeader = .none
-        let signedBodyValue: AWSSignedBodyValue = .empty
-        let signingConfig = AWSSigningConfig(credentials: credentials,
-                                             signedBodyHeader: signedBodyHeader,
-                                             signedBodyValue: signedBodyValue,
-                                             flags: flags,
-                                             date: date,
-                                             service: signingName,
-                                             region: region,
-                                             signatureType: .requestHeaders,
-                                             signingAlgorithm: .sigv4)
-        
-        // Sign request
-        guard let httpRequest = await signer.sigV4SignedRequest(
-            requestBuilder: requestBuilder,
-            signingConfig: signingConfig
-        ) else {
-            return urlRequest
-        }
-        
-        // Update original request with new headers
-        return setHeaders(from: httpRequest, to: urlRequest)
-    }
-    
-    static func setHeaders(from sdkRequest: SmithyHTTPAPI.HTTPRequest, to urlRequest: URLRequest) -> URLRequest {
-        var urlRequest = urlRequest
-        for header in sdkRequest.headers.headers {
-            urlRequest.setValue(header.value.joined(separator: ","), forHTTPHeaderField: header.name)
-        }
-        return urlRequest
-    }
-    
-    static func createAppSyncSdkHttpRequestBuilder(urlRequest: URLRequest) throws -> HTTPRequestBuilder? {
-        
-        guard let url = urlRequest.url,
-              let host = url.host else {
-            return nil
-        }
-        
-        let headers = urlRequest.allHTTPHeaderFields ?? [:]
-        let httpMethod = (urlRequest.httpMethod?.uppercased())
-            .flatMap(HTTPMethodType.init(rawValue:)) ?? .get
-        
-        let queryItems = URLComponents(url: url, resolvingAgainstBaseURL: false)?.queryItems?
-            .map { URIQueryItem(name: $0.name, value: $0.value)} ?? []
-        
-        let requestBuilder = HTTPRequestBuilder()
-            .withHost(host)
-            .withPath(url.path)
-            .withQueryItems(queryItems)
-            .withMethod(httpMethod)
-            .withPort(443)
-            .withProtocol(.https)
-            .withHeaders(.init(headers))
-            .withBody(.data(urlRequest.httpBody))
-        
-        return requestBuilder
-    }
-}
-
-extension AWSPluginsCore.AWSCredentials {
-    
-    func toAWSSDKCredentials() throws -> AWSCredentialIdentity {
-        if let tempCredentials = self as? AWSTemporaryCredentials {
-            return AWSCredentialIdentity(
-                accessKey: tempCredentials.accessKeyId,
-                secret: tempCredentials.secretAccessKey,
-                expiration: tempCredentials.expiration,
-                sessionToken: tempCredentials.sessionToken
-            )
-        } else {
-            return AWSCredentialIdentity(
-                accessKey: accessKeyId,
-                secret: secretAccessKey,
-                expiration: nil
-            )
-        }
-    }
-}
-```
-
-Then, create an `IAMAuthorizer` with this helper class.
+If you are using Amplify Auth, you can initialize `IAMAuthorizer` with a helper method from `AWSCognitoAuthPlugin` like below:
 
 ```swift
 let authorizer = IAMAuthorizer(
-  signRequest: AppSyncEventsSigner.createAppSyncSigner(region: "region")
+  signRequest: AWSCognitoAuthPlugin.createAppSyncSigner(region: "region")
 )
 ```