Scripting in Swift For a Testable Build - iOS Conf SG, Singapore, January 2020

Abstract:

Underlying many large iOS projects is a tangled nest of bash scripts that developers are often afraid to touch for fear of breaking something, and which is littered with print statements from generations of developers trying to figure out how on earth it works. How can we move away from this mess and to something more sustainable? Ellen will discuss moving a codebase like this to a command line tool that can be called from a Swift script, and which can be tested and breakpointed, and just might save a tiny bit of your sanity.

Transcript

1. SCRIPTING IN SWIFT FOR A
   TESTABLE BUILD
   IOS CONF SG | SINGAPORE | JANUARY 2020
   ELLEN SHAPIRO | @DESIGNATEDNERD | APOLLOGRAPHQL.COM
   

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3. SINGAPORE NOW
   @CARROT_App
   

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4. MADISON NOW
   @CARROT_App
   

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5. YOUR IOS PROJECT HAS
   A NEST OF BASH SCRIPTS
   @DesignatedNerd
   

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6. YOUR IOS PROJECT HAS
   A NEST OF BASH SCRIPTS
   (IT'S OKAY, MY PROJECTS DO TOO)
   @DesignatedNerd
   

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7. @DesignatedNerd
   

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9. SPOILER:
   THERE IS A BETTER WAY
   @DesignatedNerd
   

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10. SCRIPTING WITH
    ✨
    SWIFT
    @DesignatedNerd
    

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11. @DesignatedNerd
    

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12. !
    HOW DOES APOLLO WORK?
    @DesignatedNerd
    

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13. !
    HOW DOES APOLLO WORK?
    (THE SHORT VERSION)
    @DesignatedNerd
    

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14. GraphQL
    @DesignatedNerd
    

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15. SCHEMA + QUERIES = CODE
    @DesignatedNerd
    

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16. SCHEMA + QUERIES = CODE
    @DesignatedNerd
    

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17. SCHEMA + QUERIES = CODE
    WHAT IS POSSIBLE?
    @DesignatedNerd
    

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18. SCHEMA + QUERIES = CODE
    @DesignatedNerd
    

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19. SCHEMA + QUERIES = CODE
    WHAT AM I ASKING FOR?
    @DesignatedNerd
    

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20. SCHEMA + QUERIES = CODE
    @DesignatedNerd
    

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21. SCHEMA + QUERIES = CODE
    IS WHAT I'M ASKING FOR POSSIBLE?
    @DesignatedNerd
    

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22. !
    @DesignatedNerd
    

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24. !
    @DesignatedNerd
    

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25. SCHEMA + QUERIES = CODE
    @DesignatedNerd
    

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26. SCHEMA + QUERIES = CODE
    HAVE SOME TYPE-SAFE CODE!
    @DesignatedNerd
    

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27. JAVASCRIPT + NODE
    @DesignatedNerd
    

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28. TYPESCRIPT + NODE
    @DesignatedNerd
    

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29. via Webcomic Name and Alex Norris
    

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30. npm =
    @DesignatedNerd
    

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32. HOW DO WE MAKE THIS
    BETTER?
    @DesignatedNerd
    

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33. !!!!
    @DesignatedNerd
    

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34. HOW DO WE MAKE THIS
    LESS TERRIBLE
    AS QUICKLY AS POSSIBLE?
    @DesignatedNerd
    

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35. BUNDLING EVERYTHING
    @DesignatedNerd
    

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36. BUNDLING EVERYTHING
    A SMALLER
    @DesignatedNerd
    

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37. BEFORE
    LOTS OF BASH YOU HAD TO WRITE
    @DesignatedNerd
    

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38. AFTER
    LOTS OF BASH I HAD TO WRITE
    @DesignatedNerd
    

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39. @DesignatedNerd
    

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40. I HATE BASH
    @DesignatedNerd
    

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41. I HATE SUCK AT BASH
    @DesignatedNerd
    

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42. TESTING AND DEBUGGING BASH:
    ¯\_(ϑ)_/¯
    @DesignatedNerd
    

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43. echo "Variable: ${VARIABLE}"
    @DesignatedNerd
    

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44. FIGURING OUT WHAT WENT WRONG
    IN BASH: ¯\_(ϑ)_/¯
    @DesignatedNerd
    

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45. !
    @DesignatedNerd
    

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46. DON'T IT ALWAYS SEEM TO GO
    THAT YOU DON'T KNOW
    WHAT YOU GOT
    'TIL IT'S GONE
    - JONI MITCHELL
    @DesignatedNerd
    

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47. LET'S DO THIS!
    @DesignatedNerd
    

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48. 1. BUILD A SWIFT FRAMEWORK
    THAT DOES WHAT YOUR SCRIPT CURRENTLY DOES
    @DesignatedNerd
    

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49. IDENTIFY WHAT YOUR SCRIPT DOES
    @DesignatedNerd
    

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50. IDENTIFY WHAT YOUR SCRIPT DOES
    (THIS SOUNDS MUCH EASIER THAN IT IS)
    @DesignatedNerd
    

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51. run_bundled_codegen.sh
    @DesignatedNerd
    

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52. WHAT APOLLO'S SCRIPT DOES
    @DesignatedNerd
    

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53. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    @DesignatedNerd
    

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54. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    NO
    @DesignatedNerd
    

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55. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    NO
    Download and unzip current version of CLI.
    @DesignatedNerd
    

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56. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    YES
    @DesignatedNerd
    

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57. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    YES
    Does the zipped version of the CLI have the correct hash
    for this version of the iOS SDK?
    @DesignatedNerd
    

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58. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    YES
    Does the zipped version of the CLI have the correct hash
    for this version of the iOS SDK?
    NO
    @DesignatedNerd
    

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59. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    YES
    Does the zipped version of the CLI have the correct hash
    for this version of the iOS SDK?
    NO
    Download and unzip current version of CLI.
    @DesignatedNerd
    

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60. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    YES
    Does the zipped version of the CLI have the correct hash
    for this version of the iOS SDK?
    YES
    @DesignatedNerd
    

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61. WHAT APOLLO'S SCRIPT DOES
    Is there a zipped version of the CLI?
    YES
    Does the zipped version of the CLI have the correct hash
    for this version of the iOS SDK?
    YES
    Unzip if needed
    @DesignatedNerd
    

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62. RUN THE CLI WITH THE PASSED IN INFORMATION
    ⬇
    GENERATE CODE
    @DesignatedNerd
    

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63. codegen:generate --target=swift
    --localSchemaFile="schema.json"
    --includes=./**/*.graphql
    --operationIdsPath=operationIdsPath.json
    --suppressSwiftMultilineStringLiterals
    ⬇
    ApolloCodegenOptions
    @DesignatedNerd
    

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64. if [ -f "${ZIP_FILE}" ]
    ⬇
    FileManager
    @DesignatedNerd
    

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65. curl
    ⬇
    URLSession
    @DesignatedNerd
    

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66. /usr/bin/shasum
    ⬇
    CommonCrypto
    @DesignatedNerd
    

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67. SEPARATION OF CONCERNS
    @DesignatedNerd
    

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68. !
    DEPENDENCY INJECTION
    @DesignatedNerd
    

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69. CODE COVERAGE
    @DesignatedNerd
    

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70. @DesignatedNerd
    

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71. @DesignatedNerd
    

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72. @DesignatedNerd
    

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73. !
    BEST PRACTICES, DUH
    @DesignatedNerd
    

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74. YOUR SCRIPTS DESERVE
    TO BE FIRST-CLASS CITIZENS
    @DesignatedNerd
    

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75. IF YOU CAN'T RELEASE YOUR APP WITHOUT IT
    TEST IT
    @DesignatedNerd
    

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76. IF YOU CAN'T RELEASE YOUR APP WITHOUT IT
    TEST IT
    (AND IT'S A LOT EASIER TO TEST IT IN SWIFT)
    @DesignatedNerd
    

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77. 2. USE THE LIBRARY IN A
    SPM EXECUTABLE
    @DesignatedNerd
    

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78. #! /usr/bin/env xcrun swift -F ../build/Debug
    @DesignatedNerd
    

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79. chmod +x main.swift
    @DesignatedNerd
    

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80. @DesignatedNerd
    

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81. @DesignatedNerd
    

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82. @DesignatedNerd
    

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83. swift run
    @DesignatedNerd
    

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84. DON'T DO THIS
    @DesignatedNerd
    

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85. CREATE IT WITH SWIFT PACKAGE MANAGER
    $ mkdir Codegen
    $ cd Codegen
    $ swift package init --type executable
    @DesignatedNerd
    

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86. Package.swift
    // swift-tools-version:5.1
    import PackageDescription
    let package = Package(
    name: "Codegen",
    products: [
    .executable(name: "Codegen", targets: ["Codegen"]),
    ],
    dependencies: [
    .package(url: "https://github.com/apollographql/apollo-ios.git", .branch("swift-codegen"))
    ],
    targets: [
    .target(name: "Codegen", dependencies: ["ApolloCodegenLib"]),
    .testTarget(name: "CodegenTests", dependencies: ["Codegen"]),
    ]
    )
    @DesignatedNerd
    

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87. Package.swift
    // swift-tools-version:5.1
    import PackageDescription
    let package = Package(
    name: "Codegen",
    products: [
    .executable(name: "Codegen", targets: ["Codegen"]),
    ],
    dependencies: [
    .package(url: "https://github.com/apollographql/apollo-ios.git", .branch("swift-codegen"))
    ],
    targets: [
    .target(name: "Codegen", dependencies: ["ApolloCodegenLib"]),
    .testTarget(name: "CodegenTests", dependencies: ["Codegen"]),
    ]
    )
    @DesignatedNerd
    

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88. Package.swift
    // swift-tools-version:5.1
    import PackageDescription
    let package = Package(
    name: "Codegen",
    products: [
    .executable(name: "Codegen", targets: ["Codegen"]),
    ],
    dependencies: [
    .package(url: "https://github.com/apollographql/apollo-ios.git", .branch("swift-codegen"))
    ],
    targets: [
    .target(name: "Codegen", dependencies: ["ApolloCodegenLib"]),
    .testTarget(name: "CodegenTests", dependencies: ["Codegen"]),
    ]
    )
    @DesignatedNerd
    

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89. Package.swift
    // swift-tools-version:5.1
    import PackageDescription
    let package = Package(
    name: "Codegen",
    products: [
    .executable(name: "Codegen", targets: ["Codegen"]),
    ],
    dependencies: [
    .package(url: "https://github.com/apollographql/apollo-ios.git", .branch("swift-codegen"))
    ],
    targets: [
    .target(name: "Codegen", dependencies: ["ApolloCodegenLib"]),
    .testTarget(name: "CodegenTests", dependencies: ["Codegen"]),
    ]
    )
    @DesignatedNerd
    

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90. Package.swift
    // swift-tools-version:5.1
    import PackageDescription
    let package = Package(
    name: "Codegen",
    products: [
    .executable(name: "Codegen", targets: ["Codegen"]),
    ],
    dependencies: [
    .package(url: "https://github.com/apollographql/apollo-ios.git", .branch("swift-codegen"))
    ],
    targets: [
    .target(name: "Codegen", dependencies: ["ApolloCodegenLib"]),
    .testTarget(name: "CodegenTests", dependencies: ["Codegen"]),
    ]
    )
    @DesignatedNerd
    

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91. Package.swift
    // swift-tools-version:5.1
    import PackageDescription
    let package = Package(
    name: "Codegen",
    products: [
    .executable(name: "Codegen", targets: ["Codegen"]),
    ],
    dependencies: [
    .package(url: "https://github.com/apollographql/apollo-ios.git", .branch("swift-codegen"))
    ],
    targets: [
    .target(name: "Codegen", dependencies: ["ApolloCodegenLib"]),
    .testTarget(name: "CodegenTests", dependencies: ["Codegen"]),
    ]
    )
    @DesignatedNerd
    

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92. @DesignatedNerd
    

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93. $SRCROOT
    @DesignatedNerd
    

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94. @DesignatedNerd
    

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95. main.swift
    print("Hello, world!")
    @DesignatedNerd
    

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96. main.swift
    import Foundation
    enum MyCodegenError: Error {
    case sourceRootNotProvided
    case sourceRootNotADirectory
    case targetDoesntExist
    }
    guard let sourceRootPath = ProcessInfo.processInfo.environment["SRCROOT"] else {
    throw MyCodegenError.sourceRootNotProvided
    }
    @DesignatedNerd
    

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97. main.swift
    import Foundation
    import ApolloCodegenLib
    enum MyCodegenError: Error {
    case sourceRootNotProvided
    case sourceRootNotADirectory
    case targetDoesntExist
    }
    guard let sourceRootPath = ProcessInfo.processInfo.environment["SRCROOT"] else {
    throw MyCodegenError.sourceRootNotProvided
    }
    guard FileManager.default.apollo_folderExists(at: sourceRootPath) else {
    throw MyCodegenError.sourceRootNotADirectory
    }
    @DesignatedNerd
    

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98. main.swift (pt. 2)
    let applicationTargetFolderURL = sourceRootURL
    .appendingPathComponent("SwiftScriptTestSPM")
    guard FileManager.default.apollo_folderExists(at: applicationTarget) else {
    throw MyCodegenError.targetDoesntExist
    }
    let scriptFolderURL = sourceRootURL.appendingPathComponent("scripts")
    let options = ApolloCodegenOptions(targetRootURL: applicationTargetFolderURL)
    do {
    try ApolloCodegen.run(from: applicationTargetFolderURL,
    with: scriptsFolderURL,
    options: options)
    } catch {
    CodegenLogger.log("ERROR: \(error.localizedDescription)")
    exit(1)
    }
    @DesignatedNerd
    

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99. main.swift (pt. 2)
    let applicationTargetFolderURL = sourceRootURL
    .appendingPathComponent("SwiftScriptTestSPM")
    guard FileManager.default.apollo_folderExists(at: applicationTarget) else {
    throw MyCodegenError.targetDoesntExist
    }
    let scriptFolderURL = sourceRootURL.appendingPathComponent("scripts")
    let options = ApolloCodegenOptions(targetRootURL: applicationTargetFolderURL)
    do {
    try ApolloCodegen.run(from: applicationTargetFolderURL,
    with: scriptsFolderURL,
    options: options)
    } catch {
    CodegenLogger.log("ERROR: \(error.localizedDescription)")
    exit(1)
    }
    @DesignatedNerd
    

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100. main.swift (pt. 2)
     let applicationTargetFolderURL = sourceRootURL
     .appendingPathComponent("SwiftScriptTestSPM")
     guard FileManager.default.apollo_folderExists(at: applicationTarget) else {
     throw MyCodegenError.targetDoesntExist
     }
     let scriptFolderURL = sourceRootURL.appendingPathComponent("scripts")
     let options = ApolloCodegenOptions(targetRootURL: applicationTargetFolderURL)
     do {
     try ApolloCodegen.run(from: applicationTargetFolderURL,
     with: scriptsFolderURL,
     options: options)
     } catch {
     CodegenLogger.log("ERROR: \(error.localizedDescription)")
     exit(1)
     }
     @DesignatedNerd
     

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101. main.swift (pt. 2)
     let applicationTargetFolderURL = sourceRootURL
     .appendingPathComponent("SwiftScriptTestSPM")
     guard FileManager.default.apollo_folderExists(at: applicationTarget) else {
     throw MyCodegenError.targetDoesntExist
     }
     let scriptFolderURL = sourceRootURL.appendingPathComponent("scripts")
     let options = ApolloCodegenOptions(targetRootURL: applicationTargetFolderURL)
     do {
     try ApolloCodegen.run(from: applicationTargetFolderURL,
     with: scriptsFolderURL,
     options: options)
     } catch {
     CodegenLogger.log("ERROR: \(error.localizedDescription)")
     exit(1)
     }
     @DesignatedNerd
     

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102. main.swift (pt. 2)
     let applicationTargetFolderURL = sourceRootURL
     .appendingPathComponent("SwiftScriptTestSPM")
     guard FileManager.default.apollo_folderExists(at: applicationTarget) else {
     throw MyCodegenError.targetDoesntExist
     }
     let scriptFolderURL = sourceRootURL.appendingPathComponent("scripts")
     let options = ApolloCodegenOptions(targetRootURL: applicationTargetFolderURL)
     do {
     try ApolloCodegen.run(from: applicationTargetFolderURL,
     with: scriptsFolderURL,
     options: options)
     } catch {
     CodegenLogger.log("ERROR: \(error.localizedDescription)")
     exit(1)
     }
     @DesignatedNerd
     

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103. IN YOUR APPLICATION PROJECT
     @DesignatedNerd
     

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104. 3.
     !
     PROFIT!
     @DesignatedNerd
     

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105. 3.
     !
     PROFIT!*
     * - BY WASTING LESS OF YOUR TIME FAFFING AROUND WITH BASH
     @DesignatedNerd
     

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106. A CAVEAT
     @DesignatedNerd
     

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107. DEVELOPERS ARE NOT
     USED TO SCRIPTING IN SWIFT
     @DesignatedNerd
     

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108. ! "
     @DesignatedNerd
     

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109. WRITE THE DOCS
     @DesignatedNerd
     

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110. COMING SOON
     TO AN APOLLO IOS SDK NEAR YOU!
     @DesignatedNerd
     

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111. OBLIGATORY SUMMARY SLIDE
     @DesignatedNerd
     

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112. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     @DesignatedNerd
     

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113. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when stuff breaks
     @DesignatedNerd
     

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114. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when (not if) stuff breaks
     @DesignatedNerd
     

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115. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when (not if) stuff breaks
     > Dissect your old scripts, rebuild in a Swift Framework
     @DesignatedNerd
     

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116. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when (not if) stuff breaks
     > Dissect your old scripts, rebuild in a Swift Framework
     > Test everything you can't release your app without
     @DesignatedNerd
     

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117. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when (not if) stuff breaks
     > Dissect your old scripts, rebuild in a Swift Framework
     > Test everything you can't release your app without
     > Use Swift Package Manager to build an executable
     @DesignatedNerd
     

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118. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when (not if) stuff breaks
     > Dissect your old scripts, rebuild in a Swift Framework
     > Test everything you can't release your app without
     > Use Swift Package Manager to build an executable
     > Run that from a build script run phase in your main app
     @DesignatedNerd
     

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119. OBLIGATORY SUMMARY SLIDE
     > Use swift to write testable script code
     > Know what broke when (not if) stuff breaks
     > Dissect your old scripts, rebuild in a Swift Framework
     > Test everything you can't release your app without
     > Use Swift Package Manager to build an executable
     > Run that from a build script run phase in your main app
     > Document the crap out of everything
     @DesignatedNerd
     

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120. !
     THANK YOU!
     @DesignatedNerd
     

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121. LINKS!
     ADOPTING SWIFT PACKAGES IN XCODE
     https://developer.apple.com/videos/play/wwdc2019/408/
     CREATING SWIFT PACKAGES
     https://developer.apple.com/videos/play/wwdc2019/410/
     @DesignatedNerd
     

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