Simplify Reusable Download Component (#756)

Author: mluisbrown

Examples/CaseStudies/SwiftUICaseStudies/04-HigherOrderReducers-ResuableOfflineDownloads/DownloadClient.swift

@@ -4,8 +4,7 @@ import Foundation
 import ReactiveSwift
 
 struct DownloadClient {
-  var cancel: (AnyHashable) -> Effect<Never, Never>
-  var download: (AnyHashable, URL) -> Effect<Action, Error>
+  var download: (URL) -> Effect<Action, Error>
 
   struct Error: Swift.Error, Equatable {}
 
@@ -17,14 +16,7 @@ struct DownloadClient {
 
 extension DownloadClient {
   static let live = DownloadClient(
-    cancel: { id in
-      .fireAndForget {
-        dependencies[id]?.observation.invalidate()
-        dependencies[id]?.task.cancel()
-        dependencies[id] = nil
-      }
-    },
-    download: { id, url in
+    download: { url in
       .init { subscriber, lifetime in
         let task = URLSession.shared.dataTask(with: url) { data, _, error in
           switch (data, error) {
@@ -42,25 +34,12 @@ extension DownloadClient {
           subscriber.send(value: .updateProgress(progress.fractionCompleted))
         }
 
-        dependencies[id] = Dependencies(
-          observation: observation,
-          task: task
-        )
-
         lifetime += AnyDisposable {
           observation.invalidate()
           task.cancel()
-          dependencies[id] = nil
         }
         task.resume()
       }
     }
   )
 }
-
-private struct Dependencies {
-  let observation: NSKeyValueObservation
-  let task: URLSessionDataTask
-}
-
-private var dependencies: [AnyHashable: Dependencies] = [:]

Examples/CaseStudies/SwiftUICaseStudies/04-HigherOrderReducers-ResuableOfflineDownloads/DownloadComponent.swift

@@ -61,8 +61,7 @@ extension Reducer {
         case .alert(.cancelButtonTapped):
           state.mode = .notDownloaded
           state.alert = nil
-          return environment.downloadClient.cancel(state.id)
-            .fireAndForget()
+          return .cancel(id: state.id)
 
         case .alert(.deleteButtonTapped):
           state.alert = nil
@@ -87,9 +86,10 @@ extension Reducer {
           case .notDownloaded:
             state.mode = .startingToDownload
             return environment.downloadClient
-              .download(state.id, state.url)
+              .download(state.url)
               .throttle(1, on: environment.mainQueue)
               .catchToEffect(DownloadComponentAction.downloadClient)
+              .cancellable(id: state.id)
 
           case .startingToDownload:
             state.alert = cancelAlert

Examples/CaseStudies/SwiftUICaseStudiesTests/02-Effects-RefreshableTests.swift

@@ -1,3 +1,4 @@
+import ReactiveSwift
 import ComposableArchitecture
 import XCTest
 
@@ -10,7 +11,7 @@ class RefreshableTests: XCTestCase {
       reducer: refreshableReducer,
       environment: .init(
         fact: .init { .init(value: "\($0) is a good number.") },
-        mainQueue: .immediate
+        mainQueue: ImmediateScheduler()
       )
     )
 
@@ -32,7 +33,7 @@ class RefreshableTests: XCTestCase {
       reducer: refreshableReducer,
       environment: .init(
         fact: .init { _ in .init(error: .init()) },
-        mainQueue: .immediate
+        mainQueue: ImmediateScheduler()
       )
     )
 
@@ -48,14 +49,14 @@ class RefreshableTests: XCTestCase {
   }
 
   func testCancellation() {
-    let mainQueue = DispatchQueue.test
+    let mainQueue = TestScheduler()
 
     let store = TestStore(
       initialState: .init(),
       reducer: refreshableReducer,
       environment: .init(
         fact: .init { .init(value: "\($0) is a good number.") },
-        mainQueue: mainQueue.eraseToAnyScheduler()
+        mainQueue: mainQueue
       )
     )
 

Examples/CaseStudies/SwiftUICaseStudiesTests/04-HigherOrderReducers-ReusableOfflineDownloadsTests.swift

@@ -19,7 +19,7 @@ class ReusableComponentsDownloadComponentTests: XCTestCase {
 
   func testDownloadFlow() {
     var downloadClient = DownloadClient.failing
-    downloadClient.download = { _, _ in self.downloadSubject.output.producer }
+    downloadClient.download = { _ in self.downloadSubject.output.producer }
 
     let store = TestStore(
       initialState: DownloadComponentState(
@@ -55,7 +55,7 @@ class ReusableComponentsDownloadComponentTests: XCTestCase {
 
   func testDownloadThrottling() {
     var downloadClient = DownloadClient.failing
-    downloadClient.download = { _, _ in self.downloadSubject.output.producer }
+    downloadClient.download = { _ in self.downloadSubject.output.producer }
 
     let store = TestStore(
       initialState: DownloadComponentState(
@@ -95,10 +95,7 @@ class ReusableComponentsDownloadComponentTests: XCTestCase {
 
   func testCancelDownloadFlow() {
     var downloadClient = DownloadClient.failing
-    downloadClient.cancel = { _ in
-      .fireAndForget { self.downloadSubject.input.sendCompleted() }
-    }
-    downloadClient.download = { _, _ in self.downloadSubject.output.producer }
+    downloadClient.download = { _ in self.downloadSubject.output.producer }
 
     let store = TestStore(
       initialState: DownloadComponentState(
@@ -135,10 +132,7 @@ class ReusableComponentsDownloadComponentTests: XCTestCase {
 
   func testDownloadFinishesWhileTryingToCancel() {
     var downloadClient = DownloadClient.failing
-    downloadClient.cancel = { _ in
-      .fireAndForget { self.downloadSubject.input.sendCompleted() }
-    }
-    downloadClient.download = { _, _ in self.downloadSubject.output.producer }
+    downloadClient.download = { _ in self.downloadSubject.output.producer }
 
     let store = TestStore(
       initialState: DownloadComponentState(
@@ -177,10 +171,7 @@ class ReusableComponentsDownloadComponentTests: XCTestCase {
 
   func testDeleteDownloadFlow() {
     var downloadClient = DownloadClient.failing
-    downloadClient.cancel = { _ in
-      .fireAndForget { self.downloadSubject.input.sendCompleted() }
-    }
-    downloadClient.download = { _, _ in self.downloadSubject.output.producer }
+    downloadClient.download = { _ in self.downloadSubject.output.producer }
 
     let store = TestStore(
       initialState: DownloadComponentState(
@@ -212,7 +203,6 @@ class ReusableComponentsDownloadComponentTests: XCTestCase {
 
 extension DownloadClient {
   static let failing = Self(
-    cancel: { _ in .failing("DownloadClient.cancel") },
-    download: { _, _ in .failing("DownloadClient.download") }
+    download: { _ in .failing("DownloadClient.download") }
   )
 }