(iOS) Onboarding flow

OnboardingCoordinator.swift

/// The list of the onboarding steps
enum OnboardingStep: String {
    case overview
    case documentScan
    case saveAndLogin
}

/// The onboarding errors
///
/// - failed: Onboarding failed with the described error
enum OnboardingError: Error {
    case failed(String)
}

/// Onboarding step coordinator
class OnboardingCoordinator {

    private weak var navigation: UINavigationController!
    private var stepManager: OnboardingStepManager!
    var steps: [OnboardingStep] = []

    /// OnboardingCoordinator initializer
    ///
    /// - Parameter navigation: The navigation controller where steps will be pushed
    ///   - data: Any onboarding data if available
    init(navigation:UINavigationController, data: OnboardingData? = nil) {
        super.init()
        self.navigation = navigation
        self.stepManager = OnboardingStepManager(navigation: navigation, coordinator: self, data: data)
        self.setUpSteps()

        //Start with 1st step if available
        if let firstStep = self.steps.first {
            self.show(step: firstStep)
        }
    }

    /// This should not be used
    private override init() {}

    /************************************=**/
    /// Set up your steps here
    private func setUpSteps() -> Void {

        self.steps = [.overview,        //Includes .editLoanDetails which is added in real time based on the user's decision to edit them
                      .documentScan ,   //Passport VC. Shows capture camera VC too
                      .saveAndLogin
                      ]

        updateSignatureStepFromSettings()
    }

    private func updateSignatureStepFromSettings() {

        let showSignature: Bool = UserDefaults.standard.bool(forKey: "showSignature")
        if !showSignature {
            let signatureIndex = self.steps.firstIndex(of: .signature)
            if let index = signatureIndex {
                self.steps.remove(at: index)
            }
        }
    }
    /************************************=**/

    /// Starts the onboarding flow
    private func show(step:OnboardingStep) -> Void {

        self.stepManager.currentStep = self.getStepIndex(for: step)
        self.getMethodFor(step: step)() { [weak self] (data: OnboardingData?) in

            guard let this = self else { return }
            this.stepManager.data = data?.copy() as? OnboardingData

            if this.stepManager.currentStep == (this.steps.count-1) {
                let firstVC = this.navigation.viewControllers.first
                if let loginVC: LoginViewController = firstVC as? LoginViewController {
                    loginVC.startDemo()
                }
            }
            else {
                this.stepManager.currentStep += 1
                this.show(step: this.steps[this.stepManager.currentStep])
            }
        }
    }

    private func getMethodFor(step: OnboardingStep) -> (@escaping(_ data: OnboardingData?) -> Void) -> Void {
        switch step {
        case .overview:
            return self.stepManager.showOverview
        case .documentScan:
            return self.stepManager.showDocumentScan
        case .saveAndLogin:
            return self.stepManager.showSaveAndLogin
        }
    }

    private func getStepIndex(for step: OnboardingStep) -> Int {
        guard let index = self.steps.firstIndex(of: step) else {
            return 0
        }
        return index
    }

    func update(stepIndex:Int) -> Void {
        self.stepManager.currentStep = stepIndex
    }

    func popViewController(with data: OnboardingData?) -> Void {
        self.stepManager.data = data?.copy() as? OnboardingData
        self.navigation.popViewController(animated: true)
    }
}

// MARK: - Step manager

/// Onboarding step
class OnboardingStepManager {

    private weak var navigation: UINavigationController!

    var data: OnboardingData?
    private weak var coordinator: OnboardingCoordinator?
    var currentStep:Int = 0

    /// Convenience OnboardingStepManager initializer
    ///
    /// - Parameters:
    ///   - navigation: The navigation controller where steps will be pushed
    ///   - coordinator: The onboarding coordinator
    ///   - data: The onboarding data model if any
    init(navigation:UINavigationController, coordinator: OnboardingCoordinator, data: OnboardingData? = nil) {
        self.navigation = navigation
        self.coordinator = coordinator
        self.data = data?.copy() as? OnboardingData
    }

    /// This should not be used
    private init() {}

    /// Welcome / overview step
    func showOverview(completion:@escaping(_ data: OnboardingData?) -> Void) -> Void {

        let welcomeVC: WelcomeVC = WelcomeVC()
        welcomeVC.stepFinishedWithSuccess = completion
        welcomeVC.data = self.data?.copy() as? OnboardingData
        welcomeVC.coordinator = self.coordinator
        welcomeVC.currentStep = currentStep
        self.navigation.pushViewController(welcomeVC, animated: true)
    }

    func showDocumentScan(completion: @escaping(_ data: OnboardingData?) -> Void) -> Void {

        let documentScanVC: DocumentScanVC = DocumentScanVC()
        documentScanVC.stepFinishedWithSuccess = completion
        documentScanVC.data = self.data?.copy() as? OnboardingData
        documentScanVC.coordinator = self.coordinator
        documentScanVC.currentStep = currentStep
        self.navigation.pushViewController(documentScanVC, animated: true)
    }

    func showSaveAndLogin(completion: @escaping(_ data: OnboardingData?) -> Void) -> Void {

        let saveAndLoginVC: SaveAndLoginVC = aveAndLoginVC()
        saveAndLoginVC.stepFinishedWithSuccess = completion
        saveAndLoginVC.data = self.data?.copy() as? OnboardingData
        saveAndLoginVC.coordinator = self.coordinator
        saveAndLoginVC.currentStep = currentStep
        self.navigation.pushViewController(saveAndLoginVC, animated: true)
    }
}