Setting Boundaries

Presented at ViDIA meetup.

Transcript

1. Setting
   Boundaries
   

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3. Francisco Díaz
   @fco_diaz
   

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4. 3
   iOS Devs
   28
   hours
   1
   project
   == Merge Conflicts
   

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5. What do we want?
   → Minimize duplication of code.
   → Develop independently without stepping on each
   other's toes.
   

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6. Feature verticals:
   → Big Panic button
   → Today widget
   → Knock
   

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7. Big Panic button:
   

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8. What needs to be done?
   → Create the button.
   → We need a way to create reports.
   → Make a backend call to save this information.
   

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9. Today widget:
   

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10. What needs to be done?
    → Create the extension button.
    → We need a way to create reports.
    → Make a backend call to save this information.
    

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11. What was it that we wanted?
    → Minimize duplication of code.
    → Develop independently without stepping on each
    other's toes.
    

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13. Let's try
    again!
    

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14. → Create the button.
    → We need a way to create reports.
    → Make a backend call to save this information.
    

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15. UI / Presentation
    Create the button.
    

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16. Business logic
    We need a way to create reports.
    

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17. Backend connection
    Make a backend call to save this information.
    

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19. To recap:
    → Minimize duplication of code.
    → Develop independently without stepping on each
    other's toes.
    

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20. We can solve any problem
    by introducing an extra
    level of indirection
    — David Wheeler
    

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21. Dependency inversion
    

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22. struct ModelDataManager {
    let APIClient: APIType
    init(APIClient: APIType) {
    self.APIClient = APIClient
    }
    }
    

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23. protocol APIType {
    func createReport(completion: JSONDictionary? -> Void)
    }
    struct API {
    private let manager: Alamofire.Manager
    init() {
    manager = Alamofire.Manager()
    }
    }
    extension API: APIType {
    func createReport(completion: JSONDictionary? -> Void) {
    manager.request(.POST, "https://some.com/api/report")
    .responseJSON { response in
    completion(response)
    }
    }
    }
    

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24. struct ModelDataManager {
    let APIClient: APIType
    init(API: APIType) {
    self.APIClient = API
    }
    static func defaultManager() -> ModelDataManager {
    let APIClient = API()
    return ModelDataManager(API: APIClient)
    }
    func createReport(completionHandler completion: Report? -> Void) {
    APIClient.createReport() { jsonDictionary in
    let report = ... // Parse jsonDictionary into Report
    completion(report)
    }
    }
    }
    

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25. Benefits
    → Testable.
    → Decoupled.
    → Easy to fake our networking layer.
    

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27. struct FakeAPI: APIType {
    func createReport(completion: JSONDictionary? -> Void) {
    let dictionary = ["id": 12345]
    completion(dictionary)
    }
    }
    

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28. struct ModelDataManager {
    let APIClient: APIType
    init(API: APIType) {
    self.APIClient = API
    }
    static func defaultManager() -> ModelDataManager {
    // let APIClient = API()
    let APIClient = FakeAPI()
    return ModelDataManager(API: APIClient)
    }
    }
    

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29. Questions?
    Slides are available at:
    https://github.com/fdiaz/settings-boundaries-talk
    References:
    Architecture: The Lost Years
    The Clean Architecture
    

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