feat(Crypto List): Load more data

CryptoWidgetKitApp.xcodeproj/project.pbxproj

@@ -11,7 +11,6 @@
 		4D72664C2C049D800035E348 /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D72664B2C049D800035E348 /* ContentView.swift */; };
 		4D72664E2C049D810035E348 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 4D72664D2C049D810035E348 /* Assets.xcassets */; };
 		4D7266512C049D810035E348 /* Preview Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 4D7266502C049D810035E348 /* Preview Assets.xcassets */; };
-		4D72665B2C049D820035E348 /* CryptoWidgetKitAppTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D72665A2C049D820035E348 /* CryptoWidgetKitAppTests.swift */; };
 		4D8251B32C05CDDB00DD32A3 /* CryptoModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251B22C05CDDB00DD32A3 /* CryptoModel.swift */; };
 		4D8251B62C05D21D00DD32A3 /* CryptoAPIService.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251B52C05D21D00DD32A3 /* CryptoAPIService.swift */; };
 		4D8251B82C05D2A200DD32A3 /* CryptoAPIEndpoint.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251B72C05D2A100DD32A3 /* CryptoAPIEndpoint.swift */; };
@@ -21,6 +20,8 @@
 		4D8251C62C05EAD700DD32A3 /* HTTPMethod.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251C52C05EAD700DD32A3 /* HTTPMethod.swift */; };
 		4D8251C82C05EBBB00DD32A3 /* MockURLSession.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251C72C05EBBB00DD32A3 /* MockURLSession.swift */; };
 		4D8251CA2C05EC4500DD32A3 /* URLSessionProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251C92C05EC4500DD32A3 /* URLSessionProtocol.swift */; };
+		4D8251D12C0879E800DD32A3 /* View+.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251D02C0879E800DD32A3 /* View+.swift */; };
+		4D8251D32C0DAD5000DD32A3 /* CryptoViewModelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D8251D22C0DAD5000DD32A3 /* CryptoViewModelTests.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -40,7 +41,6 @@
 		4D72664D2C049D810035E348 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
 		4D7266502C049D810035E348 /* Preview Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = "Preview Assets.xcassets"; sourceTree = "<group>"; };
 		4D7266562C049D820035E348 /* CryptoWidgetKitAppTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = CryptoWidgetKitAppTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
-		4D72665A2C049D820035E348 /* CryptoWidgetKitAppTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CryptoWidgetKitAppTests.swift; sourceTree = "<group>"; };
 		4D8251B22C05CDDB00DD32A3 /* CryptoModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CryptoModel.swift; sourceTree = "<group>"; };
 		4D8251B52C05D21D00DD32A3 /* CryptoAPIService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CryptoAPIService.swift; sourceTree = "<group>"; };
 		4D8251B72C05D2A100DD32A3 /* CryptoAPIEndpoint.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CryptoAPIEndpoint.swift; sourceTree = "<group>"; };
@@ -50,6 +50,8 @@
 		4D8251C52C05EAD700DD32A3 /* HTTPMethod.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HTTPMethod.swift; sourceTree = "<group>"; };
 		4D8251C72C05EBBB00DD32A3 /* MockURLSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MockURLSession.swift; sourceTree = "<group>"; };
 		4D8251C92C05EC4500DD32A3 /* URLSessionProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = URLSessionProtocol.swift; sourceTree = "<group>"; };
+		4D8251D02C0879E800DD32A3 /* View+.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "View+.swift"; sourceTree = "<group>"; };
+		4D8251D22C0DAD5000DD32A3 /* CryptoViewModelTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CryptoViewModelTests.swift; sourceTree = "<group>"; };
 		4D8251E42C0F7B0300DD32A3 /* CryptoWidgetKitApp.xctestplan */ = {isa = PBXFileReference; lastKnownFileType = text; path = CryptoWidgetKitApp.xctestplan; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -96,6 +98,7 @@
 				4D72664B2C049D800035E348 /* ContentView.swift */,
 				4D8251B12C05CDC400DD32A3 /* Models */,
 				4D8251B92C05DA6000DD32A3 /* ViewModels */,
+				4D8251CC2C0878B900DD32A3 /* Views */,
 				4D8251B42C05D20B00DD32A3 /* Network */,
 				4D7266732C049D930035E348 /* Resources */,
 				4D72664F2C049D810035E348 /* Preview Content */,
@@ -117,7 +120,7 @@
 				4D8251E42C0F7B0300DD32A3 /* CryptoWidgetKitApp.xctestplan */,
 				4D8251C02C05E9F100DD32A3 /* Mocks */,
 				4D8251C12C05E9FE00DD32A3 /* Network */,
-				4D72665A2C049D820035E348 /* CryptoWidgetKitAppTests.swift */,
+				4D8251D22C0DAD5000DD32A3 /* CryptoViewModelTests.swift */,
 			);
 			path = CryptoWidgetKitAppTests;
 			sourceTree = "<group>";
@@ -182,6 +185,22 @@
 			path = Utils;
 			sourceTree = "<group>";
 		};
+		4D8251CC2C0878B900DD32A3 /* Views */ = {
+			isa = PBXGroup;
+			children = (
+				4D8251CF2C0879D400DD32A3 /* Extensions */,
+			);
+			path = Views;
+			sourceTree = "<group>";
+		};
+		4D8251CF2C0879D400DD32A3 /* Extensions */ = {
+			isa = PBXGroup;
+			children = (
+				4D8251D02C0879E800DD32A3 /* View+.swift */,
+			);
+			path = Extensions;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXNativeTarget section */
@@ -286,6 +305,7 @@
 				4D8251B32C05CDDB00DD32A3 /* CryptoModel.swift in Sources */,
 				4D8251B62C05D21D00DD32A3 /* CryptoAPIService.swift in Sources */,
 				4D72664C2C049D800035E348 /* ContentView.swift in Sources */,
+				4D8251D12C0879E800DD32A3 /* View+.swift in Sources */,
 				4D8251B82C05D2A200DD32A3 /* CryptoAPIEndpoint.swift in Sources */,
 				4D8251C62C05EAD700DD32A3 /* HTTPMethod.swift in Sources */,
 				4D72664A2C049D800035E348 /* CryptoWidgetKitApp.swift in Sources */,
@@ -299,7 +319,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				4D8251C82C05EBBB00DD32A3 /* MockURLSession.swift in Sources */,
-				4D72665B2C049D820035E348 /* CryptoWidgetKitAppTests.swift in Sources */,
+				4D8251D32C0DAD5000DD32A3 /* CryptoViewModelTests.swift in Sources */,
 				4D8251BF2C05E9BB00DD32A3 /* CryptoAPIServiceTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

CryptoWidgetKitApp/ContentView.swift

@@ -14,26 +14,38 @@
     var body: some View {
         @Bindable var cryptoViewModel = cryptoViewModel
         NavigationStack {
-            List(cryptoViewModel.cryptos, id: \.coinInfo.id) { crypto in
-                HStack {
-                    Text(crypto.coinInfo.fullName)
-                    Spacer()
-                    Text(crypto.display?.usd.price ?? "0")
+            List {
+                ForEach(cryptoViewModel.cryptos, id: \.coinInfo.id){ crypto in
+                    HStack {
+                        Text(crypto.coinInfo.fullName)
+                        Spacer()
+                        Text(crypto.display?.usd.price ?? "0")
+                    }
                 }
-            }
-            .redacted(reason: cryptoViewModel.isLoading ? .placeholder : [])
-            .task { await cryptoViewModel.fetch() }
-            .refreshable { await cryptoViewModel.fetch() }
-            .alert(isPresented: $cryptoViewModel.showError, content: {
-                Alert(title: Text("An error occurred, try again later"),
-                      dismissButton: .default(
-                        Text("Retry"),
-                        action: {
+                if !cryptoViewModel.showSkeleton {
+                    Section {
+                        Button(action: {
                             Task {
-                                await cryptoViewModel.fetch()
+                                await cryptoViewModel.loadMoreData()
+                            }
+                        }, label: {
+                            if cryptoViewModel.isLoading {
+                                ProgressView()
+                            } else {
+                                Text("Load more")
                             }
-                        }))
-            })
+                        })
+                    }
+                }
+            }
+            .redacted(reason: cryptoViewModel.showSkeleton ? .placeholder : [])
+            .task { await cryptoViewModel.fetchInitialData() }
+            .refreshable { await cryptoViewModel.refreshData() }
+            .errorAlert(isPresented: $cryptoViewModel.showError) {
+                Task {
+                    await cryptoViewModel.refreshData()
+                }
+            }
             .toolbar {
                 ToolbarItemGroup(placement: .bottomBar) {
                     Text("API Cache 120 seconds")

CryptoWidgetKitApp/CryptoWidgetKitApp.swift

@@ -8,7 +8,23 @@
 import SwiftUI
 
 @main
-struct CryptoWidgetKitApp: App {
+struct CryptoWidgetKitApp {
+
+    static func main() {
+        guard isProduction() else {
+            TestApp.main()
+            return
+        }
+        ProductionApp.main()
+    }
+
+    private static func isProduction() -> Bool {
+        return NSClassFromString("XCTestCase") == nil
+    }
+}
+
+// MARK: - ProductionApp
+struct ProductionApp: App {
 
     @State var cryptoViewModel = CryptoViewModel()
 
@@ -19,3 +35,10 @@
         }
     }
 }
+
+// MARK: - TestApp
+struct TestApp: App {
+    var body: some Scene {
+        WindowGroup {}
+    }
+}

CryptoWidgetKitApp/Network/CryptoAPIService.swift

@@ -6,13 +6,20 @@
 //
 
 import Foundation
+import os
 
 // MARK: - CryptoAPIService
 class CryptoAPIService {
 
     // MARK: - Dependencies
     private let session: URLSessionProtocol
 
+    // MARK: - Properties
+    private static let logger = Logger(
+        subsystem: Bundle.main.bundleIdentifier!,
+        category: String(describing: CryptoAPIService.self)
+    )
+
     // MARK: - Init
     init(session: URLSessionProtocol) {
         self.session = session
@@ -28,9 +35,11 @@ extension CryptoAPIService {
 
     /// Fetches the list of cryptocurrencies
     /// - Returns: An array of `Crypto` objects.
-    func fetchRetrieveFullList() async throws -> Cryptos {
-        let request: URLRequest = .init(endpoint: .fullList, method: .get)
+    func fetchRetrieveTopList(page: Int? = nil) async throws -> Cryptos {
+        let request: URLRequest = .init(endpoint: .topList(page: page), method: .get)
+        Self.logger.debug("Fetching top list with request: \(request)")
         let (data, _) = try await session.data(for: request)
+        Self.logger.debug("Received response with data: \(data)")
         return try JSONDecoder().decode(Cryptos.self, from: data)
     }
 }

CryptoWidgetKitApp/Network/Utils/CryptoAPIEndpoint.swift

@@ -9,15 +9,21 @@ import Foundation
 
 // MARK: - CryptoAPIEndpoint
 enum CryptoAPIEndpoint {
-    case fullList
+    case topList(page: Int?)
 }
 
 extension CryptoAPIEndpoint {
 
     var url: URL {
         switch self {
-        case .fullList:
-            URL(string: "https://min-api.cryptocompare.com/data/top/totalvolfull?tsym=USD")!
+        case .topList(let page):
+            var components = URLComponents(string: "https://min-api.cryptocompare.com/data/top/totalvolfull")!
+            var queryItems = [URLQueryItem(name: "tsym", value: "USD")]
+            if let page = page {
+                queryItems.append(URLQueryItem(name: "page", value: String(page)))
+            }
+            components.queryItems = queryItems
+            return components.url!
         }
     }
 }

CryptoWidgetKitApp/ViewModels/CryptoViewModel.swift

@@ -11,11 +11,21 @@ import Foundation
 @Observable
 final class CryptoViewModel {
 
-    // MARK: - Properties
+    // MARK: - Published Properties
     private(set) var cryptos: [Crypto] = []
-    private(set) var isLoading: Bool = true
+    private(set) var showSkeleton: Bool = false
+    private(set) var isLoading: Bool = false
     var showError: Bool = false
 
+    // MARK: - Private Properties
+    private var page: Int = 0 {
+        didSet {
+            if page < 0 {
+                page = 0
+            }
+        }
+    }
+
     // MARK: - Dependencies
     private let apiService: CryptoAPIService
 
@@ -31,15 +41,63 @@ final class CryptoViewModel {
 extension CryptoViewModel {
 
     /// Fetch the cryptos from API and update the cryptos array
-    func fetch() async {
-        isLoading = true
+    func fetchInitialData() async {
+        showSkeleton = true
+        defer { 
+            if !showError {
+                showSkeleton = false
+            }
+        }
+        await fetchData(page: nil)
+    }
+
+    /// Load more cryptos from API and append to the cryptos array
+    func loadMoreData() async {
+        page += 1
+        await fetchData(page: page)
+    }
+
+    /// Refresh all data from API and update the cryptos array
+    func refreshData() async {
+        showSkeleton = true
+        defer {
+            if !showError {
+                showSkeleton = false
+            }
+        }
+        var allData: [Crypto] = []
+        for p in 0...page {
+            do {
+                let data = try await apiService.fetchRetrieveTopList(page: p).data
+                allData.append(contentsOf: data)
+            } catch {
+                showError = true
+                return
+            }
+        }
+        cryptos = allData
+    }
+}
+
+// MARK: - Private Methods
+private extension CryptoViewModel {
+
+    /// Method to fetch data from API and update the cryptos array
+    func fetchData(page: Int?) async {
+        if page != nil {
+            isLoading = true
+        }
+        defer { isLoading = false }
         do {
-            sleep(3)
-            cryptos = try await apiService.fetchRetrieveFullList().data
-            isLoading = false
+            let data = try await apiService.fetchRetrieveTopList(page: page).data
+            if page != nil && page! > 0 {
+                cryptos.append(contentsOf: data)
+            } else {
+                cryptos = data
+            }
         } catch {
-            print(error)
             showError = true
+            self.page = (page ?? 0) - 1
         }
     }
 }

CryptoWidgetKitApp/Views/Extensions/View+.swift

@@ -0,0 +1,20 @@
+//
+//  View+.swift
+//  CryptoWidgetKitApp
+//
+//  Created by Jose Jesus Torronteras Hernandez on 30/5/24.
+//
+
+import SwiftUI
+
+extension View {
+
+    func errorAlert(isPresented: Binding<Bool>, retryAction: @escaping () -> Void) -> some View {
+        alert(isPresented: isPresented) {
+            Alert(
+                title: Text("An error occurred, try again later"),
+                dismissButton: .default(Text("Retry"), action: retryAction)
+            )
+        }
+    }
+}