Swift: How to handle errors from the Swift SDK

swift/example_code/swift-sdk/ErrorHandling/.gitignore

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+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/
+DerivedData/
+.swiftpm/config/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

swift/example_code/swift-sdk/ErrorHandling/Package.swift

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+// swift-tools-version: 5.5
+// The swift-tools-version declares the minimum version of Swift required to
+// build this package.
+//
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import PackageDescription
+
+let package = Package(
+    name: "ErrorHandling",
+    // Let Xcode know the minimum Apple platforms supported.
+    platforms: [
+        .macOS(.v11),
+        .iOS(.v13)
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        .package(
+            url: "https://github.com/awslabs/aws-sdk-swift",
+            from: "0.34.0"
+        ),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package, defining a module or a test suite.
+        // Targets can depend on other targets in this package and products from dependencies.
+        .executableTarget(
+            name: "ErrorHandling",
+            dependencies: [
+                .product(name: "AWSS3", package: "aws-sdk-swift"),
+            ],
+            path: "Sources"),
+    ]
+)

swift/example_code/swift-sdk/ErrorHandling/Sources/entry.swift

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+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+//
+// An example showing how to handle service and HTTP errors when using the AWS
+// SDK for Swift.
+import Foundation
+import AwsCommonRuntimeKit
+import ClientRuntime
+import AWSS3
+
+/// Main entry point.
+@main
+struct ErrorHandlingExample {
+    static func main() async {
+        await SDKLoggingSystem.initialize(logLevel: .error)
+
+        print("Calling ListBuckets using a Region name that doesn't exist. This")
+        print("should result in a DNS resolution error.")
+
+        // snippet-start:[errors.swift.service-error]
+        do {
+            let client = try S3Client(region: "un-real-1")
+
+            _ = try await client.listBuckets(input: ListBucketsInput())
+            print("Done")
+        } catch let error as CommonRunTimeError {
+            switch error {
+                case .crtError(let error):
+                    print("Common RunTime error: (code \(error.code)) (\(error.name)): \(error.message)")
+                    break
+                default:
+                    // This should never happen in current versions of the
+                    // SDK, but is here to future-proof this error handler.
+                    dump(error, name: "Unknown type of CommonRunTimeError")
+            }
+        } catch let error as CRTError {
+            print("CRT Error (code \(error.code)) (\(error.name)): \(error.message)")
+        } catch {
+            print("Some other error")
+        }
+        // snippet-end:[errors.swift.service-error]
+
+        print("\n\n")
+        print("Calling GetObject with bucket and key names that likely don't")
+        print("exist. If that's the case, this will result in an HTTP error 403")
+        print("(Forbidden).")
+
+        // snippet-start:[errors.swift.http-error]
+        do {
+            let client = try S3Client(region: "us-east-1")
+
+            _ = try await client.getObject(input: GetObjectInput(
+                bucket: "not-a-real-bucket",
+                key: "not-a-real-key"
+            ))
+            print("Found a matching bucket but shouldn't have!")
+        } catch let error as HTTPError {
+            print("HTTP error; status code: \(error.httpResponse.statusCode.rawValue)")
+        } catch {
+            dump(error)
+        }
+        // snippet-end:[errors.swift.http-error]
+    }
+}