Swift: Presigned URLs, downloads, multi-part uploads (#7030)

Swift presigned URLs, downloads, and multi-part uploads

Author: shepazon

swift/example_code/s3/presigned-urls/Package.swift

@@ -0,0 +1,38 @@
+// swift-tools-version: 5.9
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+//
+// The swift-tools-version declares the minimum version of Swift required to
+// build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "presigned",
+    // Let Xcode know the minimum Apple platforms supported.
+    platforms: [
+        .macOS(.v13),
+        .iOS(.v15)
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        .package(
+            url: "https://github.com/awslabs/aws-sdk-swift",
+            from: "1.0.0"),
+        .package(
+            url: "https://github.com/apple/swift-argument-parser.git",
+            branch: "main"
+        )
+    ],
+    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: "presigned",
+            dependencies: [
+                .product(name: "AWSS3", package: "aws-sdk-swift"),
+                .product(name: "ArgumentParser", package: "swift-argument-parser"),
+            ],
+            path: "Sources")
+    ]
+)

swift/example_code/s3/presigned-urls/Sources/TransferDirection.swift

@@ -0,0 +1,13 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import Foundation
+import ArgumentParser
+
+/// Flags used to identify whether the file is to be uploaded or downloaded.
+enum TransferDirection: String, EnumerableFlag {
+    /// The file transfer is an upload.
+    case up
+    /// The file transfer is a download.
+    case down
+}

swift/example_code/s3/presigned-urls/Sources/TransferError.swift

@@ -0,0 +1,47 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+/// Errors thrown by the example's functions.
+enum TransferError: Error {
+    /// The destination directory for a download is missing or inaccessible.
+    case directoryError
+    /// An error occurred while downloading a file from Amazon S3.
+    case downloadError(_ message: String = "")
+    /// An error occurred moving the file to its final destination.
+    case fileMoveError
+    /// An error occurred when completing a multi-part upload to Amazon S3.
+    case multipartFinishError
+    /// An error occurred when starting a multi-part upload to Amazon S3.
+    case multipartStartError
+    /// An error occurred while uploading a file to Amazon S3.
+    case uploadError(_ message: String = "")
+    /// An error occurred while reading the file's contents.
+    case readError
+    /// An error occurred while presigning the URL.
+    case signingError
+    /// An error occurred while writing the file's contents.
+    case writeError
+
+    var errorDescription: String? {
+        switch self {
+        case .directoryError:
+            return "The destination directory could not be located or created"
+        case .downloadError(message: let message):
+            return "An error occurred attempting to download the file: \(message)"
+        case .fileMoveError:
+            return "The file couldn't be moved to the destination directory"
+        case .multipartFinishError:
+            return "An error occurred when completing a multi-part upload to Amazon S3."
+        case .multipartStartError:
+            return "An error occurred when starting a multi-part upload to Amazon S3."
+        case .uploadError(message: let message):
+            return "An error occurred attempting to upload the file: \(message)"
+        case .readError:
+            return "An error occurred while reading the file data"
+        case .signingError:
+            return "An error occurred while pre-signing the URL"
+        case .writeError:
+            return "An error occurred while writing the file data"
+        }
+    }
+}