[iOS Dev UK 23] Making developer tools with Swift

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Making developer tools with Swift Pol Piella Abadia Senior iOS Developer, BBC iPlayer iOS Dev UK · Aberystwyth, Wales 10:20 Great Hall

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Senior software engineer based in Manchester Hi! I’m Pol

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Content creation Apps I am working on Public speaking

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Content creation Apps I am working on Public speaking

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Content creation Apps I am working on Public speaking

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Swift & Developer Tools?

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Swift & Developer Tools!

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You know Swift!

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You (and your team) know Swift!

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Focus on the system and NOT the language!

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You (and your audience) know Swift!

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Can you build it with Swift?

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#1 A simple CLI script?

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feature/MYTICKET-123_name-of-your-branch

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feature/MYTICKET-123_name-of-your-branch Author: Pol Piella Abadia Date: Sun Aug 20 14:03:41 2023 +0100 My awesome feature TICKET-123 Branch Commit

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# ! /usr/bin/env swift import Foundation let commitMessageFile = CommandLine.arguments[1] guard let data = FileManager.default.contents(atPath: commitMessageFile), let commitMessage = String(data: data, encoding: .utf8) else { exit(1) } let gitBranchName = shell("git rev-parse -- abbrev-ref HEAD") .trimmingCharacters(in: .newlines) let regex = try! NSRegularExpression(pattern: #"(\w+-\d+)"#, options: .anchorsMatchLines) let stringRange = NSRange(location: 0, length: gitBranchName.utf16.count) guard let match = regex.firstMatch(in: gitBranchName, range: stringRange) else { exit(0) } let range = match.range(at: 1) guard !NSEqualRanges(range, NSMakeRange(NSNotFound, 0)) else { exit(1) } let ticketNumber = (gitBranchName as NSString) .substring(with: range) .trimmingCharacters(in: .newlines) if !commitMessage.contains(ticketNumber) { do { try "\(commitMessage.trimmingCharacters(in:.newlines))\n\n\(ticketNumber)" .write(toFile: commitMessageFile, atomically: true, encoding: .utf8) } catch { print("Could not write to file \(commitMessageFile)") } }

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chmod +x file_where_hook_code_is

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Not so fast…

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Yes and no… https://github.com/mxcl/swift-sh

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# ! /usr/bin/env swift-sh import Foundation let commitMessageFile = CommandLine.arguments[1] guard let data = FileManager.default.contents(atPath: commitMessageFile), let commitMessage = String(data: data, encoding: .utf8) else { exit(1) } let gitBranchName = shell("git rev-parse -- abbrev-ref HEAD") .trimmingCharacters(in: .newlines) let regex = try! NSRegularExpression(pattern: #"(\w+-\d+)"#, options: .anchorsMatchLines) let stringRange = NSRange(location: 0, length: gitBranchName.utf16.count) guard let match = regex.firstMatch(in: gitBranchName, range: stringRange) else { exit(0) } let range = match.range(at: 1) guard !NSEqualRanges(range, NSMakeRange(NSNotFound, 0)) else { exit(1) } let ticketNumber = (gitBranchName as NSString) .substring(with: range) .trimmingCharacters(in: .newlines) if !commitMessage.contains(ticketNumber) { do { try "\(commitMessage.trimmingCharacters(in:.newlines))\n\n\(ticketNumber)" .write(toFile: commitMessageFile, atomically: true, encoding: .utf8) } catch { print("Could not write to file \(commitMessageFile)") } }

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# ! /usr/bin/env swift-sh import Foundation import SourceKittenFramework // @jpsim ~> 0.34.1 let commitMessageFile = CommandLine.arguments[1] guard let data = FileManager.default.contents(atPath: commitMessageFile), let commitMessage = String(data: data, encoding: .utf8) else { exit(1) } let gitBranchName = shell("git rev-parse -- abbrev-ref HEAD") .trimmingCharacters(in: .newlines) let regex = try! NSRegularExpression(pattern: #"(\w+-\d+)"#, options: .anchorsMatchLines) let stringRange = NSRange(location: 0, length: gitBranchName.utf16.count) guard let match = regex.firstMatch(in: gitBranchName, range: stringRange) else { exit(0) } let range = match.range(at: 1) guard !NSEqualRanges(range, NSMakeRange(NSNotFound, 0)) else { exit(1) } let ticketNumber = (gitBranchName as NSString) .substring(with: range) .trimmingCharacters(in: .newlines) if !commitMessage.contains(ticketNumber) { do { try "\(commitMessage.trimmingCharacters(in:.newlines))\n\n\(ticketNumber)" .write(toFile: commitMessageFile, atomically: true, encoding: .utf8) } catch { print("Could not write to file \(commitMessageFile)") } }

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Future- proofing and scaling

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swift package init -- type executable

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// swift-tools-version: 5.9 import PackageDescription let package = Package( name: "GitHookExecutable", dependencies: [ ], targets: [ .executableTarget( name: "GitHookExecutable", dependencies: [ ] ), ] )

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// swift-tools-version: 5.9 import PackageDescription let package = Package( name: "GitHookExecutable", dependencies: [ .package(url: "https: // github.com/apple/swift-argument-parser.git", exact: "1.2.3") ], targets: [ .executableTarget( name: "GitHookExecutable", dependencies: [ .product(name: "ArgumentParser", package: "swift-argument-parser") ] ), ] )

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import ArgumentParser @main struct GitHookExecutable: ParsableCommand { @Argument(help: "The path to the commit message file") var commitMessagePath: String func run() throws { let commitMessage = try String(contentsOfFile: commitMessagePath) // . .. } }

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Learn more about it! https://www.youtube.com/watch?v=yyOXynCoagE&t=611s

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#2 Running a build script?

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brew install swiftlint pod install

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What about Swift Packages?

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Swift 5.6 to the rescue! https://github.com/apple/swift-evolution/blob/main/proposals/0303-swiftpm-extensible-build-tools.md

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// swift-tools-version:5.7 import PackageDescription let package = Package( name: "SwiftLint", platforms: [.macOS(.v12)], products: [ .plugin(name: "SwiftLintPlugin", targets: ["SwiftLintPlugin"]) ], dependencies: [ / / .. . ], targets: [ .plugin( name: "SwiftLintPlugin", capability: .buildTool(), dependencies: [ .target(name: "SwiftLintBinary", condition: .when(platforms: [.macOS])), .target(name: "swiftlint", condition: .when(platforms: [.linux])) ] ), .executableTarget( name: "swiftlint", dependencies: [ .product(name: "ArgumentParser", package: "swift-argument-parser"), "CollectionConcurrencyKit", "SwiftLintFramework", "SwiftyTextTable", ] ), .binaryTarget( name: "SwiftLintBinary", url: "https: // github.com/realm/SwiftLint/releases/download/0.52.4/SwiftLintBinary-macos.artifactbundle.zip", checksum: "8a8095e6235a07d00f34a9e500e7568b359f6f66a249f36d12cd846017a8c6f5" ) ] ) https://github.com/realm/SwiftLint/blob/main/Package.swift

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import Foundation import PackagePlugin @main struct SwiftLintPlugin: BuildToolPlugin { func createBuildCommands(context: PluginContext, target: Target) async throws - > [Command] { guard let sourceTarget = target as? SourceModuleTarget else { return [] } return createBuildCommands( inputFiles: sourceTarget.sourceFiles(withSuffix: "swift").map(\.path), packageDirectory: context.package.directory, workingDirectory: context.pluginWorkDirectory, tool: try context.tool(named: "swiftlint") ) } private func createBuildCommands( inputFiles: [Path], packageDirectory: Path, workingDirectory: Path, tool: PluginContext.Tool ) -> [Command] { // . .. return [ .prebuildCommand( displayName: "SwiftLint", executable: tool.path, arguments: arguments, outputFilesDirectory: outputFilesDirectory ) ] } } https://github.com/realm/SwiftLint/blob/main/Plugins/SwiftLintPlugin/SwiftLintPlugin.swift

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// swift-tools-version: 5.9 import PackageDescription let package = Package( name: "DemoSwiftPackage", products: [ .library( name: "DemoSwiftPackage", targets: ["DemoSwiftPackage"] ), ], dependencies: [ .package(url: "https: // github.com/realm/SwiftLint.git", exact: "0.52.4") ], targets: [ .target( name: "DemoSwiftPackage", plugins: [ .plugin(name: "SwiftLintPlugin", package: "SwiftLint") ] ) ] )

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What about Xcode projects?

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import Foundation import PackagePlugin #if canImport(XcodeProjectPlugin) import XcodeProjectPlugin extension SwiftLintPlugin: XcodeBuildToolPlugin { func createBuildCommands(context: XcodePluginContext, target: XcodeTarget) throws - > [Command] { let inputFilePaths = target.inputFiles .filter { $0.type == .source && $0.path.extension == "swift" } .map(\.path) return createBuildCommands( inputFiles: inputFilePaths, packageDirectory: context.xcodeProject.directory, workingDirectory: context.pluginWorkDirectory, tool: try context.tool(named: "swiftlint") ) } } #endif https://github.com/realm/SwiftLint/blob/main/Plugins/SwiftLintPlugin/SwiftLintPlugin.swift

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Manually running a build script?

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import UIKit public protocol Camera { func start() func stop() func capture(_ completion: @escaping (UIImage?) -> Void) func rotate() }

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import UIKit // Protocol to be matched protocol AutoMockable {} public protocol Camera: AutoMockable { func start() func stop() func capture(_ completion: @escaping (UIImage?) -> Void) func rotate() }

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./sourcery -- config ".sourcery.yml"

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// Generated using Sourcery 1.8.2 — https: // github.com/krzysztofzablocki/Sourcery // DO NOT EDIT // swiftlint:disable line_length // swiftlint:disable variable_name import Foundation #if os(iOS) || os(tvOS) || os(watchOS) import UIKit #elseif os(OSX) import AppKit #endif class CameraMock: Camera { // MARK: - start var startCallsCount = 0 var startCalled: Bool { return startCallsCount > 0 } var startClosure: (() -> Void)? func start() { startCallsCount += 1 startClosure?() } //

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What if…

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/ / swift-tools-version:5.6 import PackageDescription import Foundation let package = Package( name: "Sourcery", platforms: [ .macOS(.v12) ], products: [ .plugin(name: "SourceryCommandPlugin", targets: ["SourceryCommandPlugin"]) ], dependencies: [], targets: [ .executableTarget( name: "SourceryExecutable", dependencies: ["SourceryLib"], path: "SourceryExecutable", exclude: [ "Info.plist" ] ), .plugin( name: "SourceryCommandPlugin", capability: .command( intent: .custom( verb: "sourcery-command", description: "Sourcery command plugin for code generation" ), permissions: [ .writeToPackageDirectory(reason: "Need permission to write generated files to package directory") ] ), dependencies: ["SourceryExecutable"] ) ] ) https://github.com/krzysztofzablocki/Sourcery/blob/master/Package.swift

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import PackagePlugin import Foundation @main struct SourceryCommandPlugin: CommandPlugin { func performCommand(context: PluginContext, arguments: [String]) async throws { / / Run one per target for target in context.package.targets { let configFilePath = target.directory.appending(subpath: ".sourcery.yml").string let sourcery = try context.tool(named: "SourceryExecutable").path.string guard FileManager.default.fileExists(atPath: configFilePath) else { Diagnostics.warning("⚠ Could not find `.sourcery.yml` for target \(target.name)") continue } let sourceryURL = URL(fileURLWithPath: sourcery) let process = Process() process.executableURL = sourceryURL process.arguments = [ " - - config", configFilePath, " - - cacheBasePath", context.pluginWorkDirectory.string ] try process.run() process.waitUntilExit() let gracefulExit = process.terminationReason = = .exit && process.terminationStatus == 0 if !gracefulExit { throw "🛑 The plugin execution failed with reason: \(process.terminationReason.rawValue) and status: \(process.terminationStatus) " } } } } https://github.com/krzysztofzablocki/Sourcery/blob/master/Plugins/SourceryCommandPlugin/SourceryCommandPlugin.swift

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// swift-tools-version: 5.9 import PackageDescription let package = Package( name: "GitHookExecutable", dependencies: [ .package(url: "https: // github.com/apple/swift-argument-parser.git", exact: "1.2.3"), .package(url: "https: // github.com/krzysztofzablocki/Sourcery.git", exact: "2.0.3") ], targets: [ .executableTarget( name: "GitHookExecutable", dependencies: [ .product(name: "ArgumentParser", package: "swift-argument-parser") ] ), ] )

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swift package sourcery-command

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What about Xcode projects?

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#if canImport(XcodeProjectPlugin) import XcodeProjectPlugin extension SourceryCommandPlugin: XcodeCommandPlugin { func performCommand(context: XcodePluginContext, arguments: [String]) throws { for target in context.xcodeProject.targets { guard let configFilePath = target .inputFiles .filter({ $0.path.lastComponent == ".sourcery.yml" }) .first? .path .string else { Diagnostics.warning("⚠ Could not find `.sourcery.yml` in Xcode's input file list") return } let sourcery = try context.tool(named: "SourceryExecutable").path.string try run(sourcery, withConfig: configFilePath, cacheBasePath: context.pluginWorkDirectory.string) } } } #endif https://github.com/krzysztofzablocki/Sourcery/blob/master/Plugins/SourceryCommandPlugin/SourceryCommandPlugin.swift

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#3 Back-End service?

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How does this work?

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Ok… but what are web hooks?

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issue_comment webhook https://docs.github.com/en/webhooks/webhook-events-and-payloads#issue_comment

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Creating a service with Swift!

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https://github.com/swift-server/swift-aws-lambda-runtime

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It’s just an executable…

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import AWSLambdaRuntime import AWSLambdaEvents @main struct UploadToTestFlightWebhook: SimpleLambdaHandler { let snakeCaseDecoder: JSONDecoder init() { let decoder = JSONDecoder() decoder.keyDecodingStrategy = .convertFromSnakeCase snakeCaseDecoder = decoder } func handle(_ request: APIGatewayV2Request, context: LambdaContext) async throws -> APIGatewayV2Response { guard let body = request.body, let bodyData = body.data(using: .utf8), let request = try? snakeCaseDecoder.decode(GithubWebhookData.self, from: bodyData) else { return .init(statusCode: .badRequest, body: "Could not parse the request content ... ") } guard request.action == "created", request.comment.body.lowercased() == "upload to testflight" else { return .init(statusCode: .ok, body: "Not handling the event ... ") } // ... } }

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… that runs on a different platform

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#! /bin/bash product=Webhook docker run \ -- rm \ -- volume "$(pwd)/:/src" \ -- workdir "/src/" \ swift:5.8-amazonlinux2 \ swift build -- product $product -c release -Xswiftc -static-stdlib target=.build/lambda/$product rm -rf "$target" mkdir -p "$target" cp ".build/release/$product" "$target/" cd "$target" ln -s "$product" "bootstrap" zip -- symlinks lambda.zip * https://fabianfett.dev/getting-started-with-swift-aws-lambda-runtime

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#! /bin/bash swift package \ -- disable-sandbox archive \ -- swift-version 5.8 \ -- output-path . \ -- products Webhook

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#! /bin/bash swift package \ -- disable-sandbox archive \ -- swift-version 5.8 \ -- output-path . \ -- products Webhook

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It’s getting better…

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You still need to upload it…

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service: upload-to-testflight-webhook frameworkVersion: "3" configValidationMode: warn package: artifact: build/Products/Webhook.zip provider: name: aws region: eu-west-1 httpApi: payload: "2.0" cors: true runtime: provided.al2 architecture: arm64 functions: webhook: handler: webhook memorySize: 256 description: "[${sls:stage}] Upload" events: - httpApi: path: /upload method: post Serverless framework https://www.serverless.com

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name: Deploy the serverless lambda to AWS on: push: branches: - main jobs: deploy: runs-on: ubuntu-latest container: image: swift:5.8-amazonlinux2 steps: - uses: actions/checkout@v3 - name: Configure AWS Credentials uses: aws-actions/configure-aws-credentials@v2 with: aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }} aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }} aws-region: eu-west-2 - name: Install zip run: | yum install -y zip - name: Install awscli run: | yum install -y awscli - name: Archive the lambda run: | ./package.sh Webhook - name: Deploy to AWS run: | aws lambda update-function-code \ - - function-name webhook \ - - zip-file fileb: // .build/lambda/Webhook/Webhook.zip CI/CD workflow https://www.polpiella.dev/automatic-deployment-of-swift-aws-lambdas-on-ci-cd

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This is jut the tip of the iceberg…

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Even slide decks! https://github.com/joshdholtz/DeckUI

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Any questions?

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Any questions? I have stickers too…

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Resources - Plugins https://www.polpiella.dev/code-generation-using-swift-package-plugins https://www.polpiella.dev/sourcery-swift-package-command-plugin https://www.polpiella.dev/load-custom-fonts-with-no-code-using-swift-package-plugins https://www.polpiella.dev/an-early-look-at-swift-extensible-build-tools https://theswiftdev.com/beginners-guide-to-swift-package-manager-command-plugins/ https://www.polpiella.dev/binary-targets-in-modern-swift-packages https://www.polpiella.dev/network-requests-in-swift-package-plugins

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https://www.polpiella.dev/automating-swift-package-releases-with-github-actions https://www.polpiella.dev/collecting-gihub-actions-workflow-metrics-with-swift https://www.polpiella.dev/scripting-in-swift-git-hooks https://github.com/artemnovichkov/Swift-For-Scripting https://blog.eidinger.info/swift-e-runs-code-directly-from-the-command-line https://nshipster.com/swift-sh/ Resources - CLI + Scripts

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https://www.areweserveryet.org/ https://www.polpiella.dev/github-webhooks-and-xcode-cloud https://www.polpiella.dev/swift-async-await-in-aws-lambdas https://www.polpiella.dev/scheduled-swift-aws-lambdas https://www.polpiella.dev/automatic-deployment-of-swift-aws-lambdas-on-ci-cd https://opticalaberration.com/2021/12/proxy-server.html Resources - ServerSide Swift https://www.serversideswift.info https://theswiftdev.com