Refactor loading parameter

Author: Alexey Naumov

CountriesSwiftUI/Interactors/CountriesInteractor.swift

@@ -12,7 +12,7 @@ import SwiftUI
 
 protocol CountriesInteractor {
     func loadCountries()
-    func load(countryDetails: Binding<Loadable<Country.Details>>, country: Country)
+    func load(countryDetails: LoadableSubject<Country.Details>, country: Country)
 }
 
 struct RealCountriesInteractor: CountriesInteractor {
@@ -26,19 +26,17 @@ struct RealCountriesInteractor: CountriesInteractor {
     }
 
     func loadCountries() {
-        let countries = appState.value.userData.countries.value
         let cancelBag = CancelBag()
-        appState[\.userData.countries] = .isLoading(last: countries, cancelBag: cancelBag)
+        appState[\.userData.countries].setIsLoading(cancelBag: cancelBag)
         weak var weakAppState = appState
         webRepository.loadCountries()
             .sinkToLoadable { weakAppState?[\.userData.countries] = $0 }
             .store(in: cancelBag)
     }
 
-    func load(countryDetails: Binding<Loadable<Country.Details>>, country: Country) {
+    func load(countryDetails: LoadableSubject<Country.Details>, country: Country) {
         let cancelBag = CancelBag()
-        countryDetails.wrappedValue = .isLoading(last: countryDetails.wrappedValue.value,
-                                                 cancelBag: cancelBag)
+        countryDetails.wrappedValue.setIsLoading(cancelBag: cancelBag)
         let countriesArray = appState
             .map { $0.userData.countries }
             .tryMap { countries -> [Country] in
@@ -64,6 +62,6 @@ struct StubCountriesInteractor: CountriesInteractor {
     func loadCountries() {
     }
 
-    func load(countryDetails: Binding<Loadable<Country.Details>>, country: Country) {
+    func load(countryDetails: LoadableSubject<Country.Details>, country: Country) {
     }
 }

CountriesSwiftUI/Interactors/ImagesInteractor.swift

@@ -11,7 +11,7 @@ import Foundation
 import SwiftUI
 
 protocol ImagesInteractor {
-    func load(image: Binding<Loadable<UIImage>>, url: URL?)
+    func load(image: LoadableSubject<UIImage>, url: URL?)
 }
 
 struct RealImagesInteractor: ImagesInteractor {
@@ -22,12 +22,12 @@ struct RealImagesInteractor: ImagesInteractor {
         self.webRepository = webRepository
     }
 
-    func load(image: Binding<Loadable<UIImage>>, url: URL?) {
+    func load(image: LoadableSubject<UIImage>, url: URL?) {
         guard let url = url else {
             image.wrappedValue = .notRequested; return
         }
         let cancelBag = CancelBag()
-        image.wrappedValue = .isLoading(last: image.wrappedValue.value, cancelBag: cancelBag)
+        image.wrappedValue.setIsLoading(cancelBag: cancelBag)
         webRepository.load(imageURL: url, width: 300)
             .sinkToLoadable {
                 image.wrappedValue = $0
@@ -37,6 +37,6 @@ struct RealImagesInteractor: ImagesInteractor {
 }
 
 struct StubImagesInteractor: ImagesInteractor {
-    func load(image: Binding<Loadable<UIImage>>, url: URL?) {
+    func load(image: LoadableSubject<UIImage>, url: URL?) {
     }
 }

CountriesSwiftUI/Utilities/Loadable.swift

@@ -7,6 +7,9 @@
 //
 
 import Foundation
+import SwiftUI
+
+typealias LoadableSubject<Value> = Binding<Loadable<Value>>
 
 enum Loadable<T> {
 
@@ -32,6 +35,10 @@ enum Loadable<T> {
 
 extension Loadable {
 
+    mutating func setIsLoading(cancelBag: CancelBag) {
+        self = .isLoading(last: value, cancelBag: cancelBag)
+    }
+    
     mutating func cancelLoading() {
         switch self {
         case let .isLoading(last, cancelBag):

CountriesSwiftUI/Utilities/NetworkingHelpers.swift

@@ -6,6 +6,7 @@
 //  Copyright © 2020 Alexey Naumov. All rights reserved.
 //
 
+import SwiftUI
 import Combine
 import Foundation
 

UnitTests/Mocks/MockedInteractors.swift

@@ -48,7 +48,7 @@ struct MockedCountriesInteractor: Mock, CountriesInteractor {
         register(.loadCountries)
     }
 
-    func load(countryDetails: Binding<Loadable<Country.Details>>, country: Country) {
+    func load(countryDetails: LoadableSubject<Country.Details>, country: Country) {
         register(.loadCountryDetails(country))
     }
 }
@@ -67,7 +67,7 @@ struct MockedImagesInteractor: Mock, ImagesInteractor {
         self.actions = .init(expected: expected)
     }
 
-    func load(image: Binding<Loadable<UIImage>>, url: URL?) {
+    func load(image: LoadableSubject<UIImage>, url: URL?) {
         register(.loadImage(url))
     }
 }