feat: added new CategorySelectionView

fix: progress bar will now be resetted correctly

QuizApp/CategorySelectionView.swift

@@ -0,0 +1,39 @@
+//
+//  CategorySelectionView.swift
+//  QuizApp
+//
+//  Created by Paul on 06.08.25.
+//
+
+import SwiftUI
+
+struct CategorySelectionView: View {
+    @ObservedObject var viewModel = ViewModel()
+    @State private var selectedCategory: String? = nil
+
+    var body: some View {
+        if viewModel.selectedCategory != nil && !viewModel.questions.isEmpty {
+            ContentView(viewModel: viewModel)
+        } else {
+            VStack(spacing: 20) {
+                Text("Wähle eine Kategorie")
+                    .font(.largeTitle)
+
+                ForEach(viewModel.availableCategories, id: \.self) { category in
+                    Button(action: {
+                        viewModel.loadQuestions(for: category)
+                        selectedCategory = category
+                    }) {
+                        Text(category)
+                            .font(.title2)
+                            .padding()
+                            .frame(maxWidth: 300)
+                            .background(Color.blue)
+                            .foregroundColor(.white)
+                            .cornerRadius(12)
+                    }
+                }
+            }
+        }
+    }
+}

QuizApp/ContentView.swift

@@ -2,7 +2,7 @@
 //  ContentView.swift
 //  QuizApp
 //
-//  Created by Paul Nowotka on 02.08.25.
+//  Created by Paul on 02.08.25.
 //
 
 import SwiftUI
@@ -31,6 +31,14 @@ struct ContentView: View {
                     .background(Color.blue)
                     .foregroundColor(.white)
                     .cornerRadius(10)
+                    
+                    Button("Zurück zur Kategorieauswahl") {
+                        viewModel.selectedCategory = nil
+                    }
+                    .padding()
+                    .background(Color.gray)
+                    .foregroundColor(.white)
+                    .cornerRadius(10)
                 }
             } else if let frage = viewModel.currentQuestion {
                 Text("Punkte: \(viewModel.score)")
@@ -132,6 +140,7 @@ struct ContentView: View {
         selectedAnswerIndex = nil
         isAnswered = false
         viewModel.answeredCount = 0
+        viewModel.selectedAnswers = Array(repeating: nil, count: viewModel.questions.count)
     }
     
     func colorForAnswer(at index: Int) -> Color {
@@ -155,5 +164,5 @@ struct ContentView: View {
 }
 
 #Preview {
-    ContentView()
+    CategorySelectionView()
 }

QuizApp/QuizAppApp.swift

@@ -2,7 +2,7 @@
 //  QuizAppApp.swift
 //  QuizApp
 //
-//  Created by Paul Nowotka on 02.08.25.
+//  Created by Paul on 02.08.25.
 //
 
 import SwiftUI
@@ -11,7 +11,7 @@ import SwiftUI
 struct QuizAppApp: App {
     var body: some Scene {
         WindowGroup {
-            ContentView()	
+            CategorySelectionView()
         }
     }
 }

QuizApp/Topic.swift

@@ -2,15 +2,13 @@
 //  Topic.swift
 //  QuizApp
 //
-//  Created by Paul Nowotka on 03.08.25.
+//  Created by Paul on 03.08.25.
 //
 
 import Foundation
 
 struct QuizQuestion: Decodable, Hashable {
-    
     let question: String
     let answers: [String]
     let correctAnswer: Int
-    
 }

QuizApp/ViewModel.swift

@@ -2,14 +2,16 @@
 //  ViewModel.swift
 //  QuizApp
 //
-//  Created by Paul Nowotka on 03.08.25.
+//  Created by Paul on 03.08.25.
 //
 
 import Foundation
 
 class ViewModel: ObservableObject {
     
+    private var allQuestionsByCategory: [String: [QuizQuestion]] = [:]
     @Published var questions: [QuizQuestion] = []
+    @Published var selectedCategory: String? = nil
     @Published var currentQuestionIndex: Int = 0
     @Published var score: Int = 0
     @Published var isQuizFinished: Bool = false
@@ -27,6 +29,11 @@ class ViewModel: ObservableObject {
             return questions[currentQuestionIndex]
         }
     
+    var availableCategories: [String] {
+        return Array(allQuestionsByCategory.keys).sorted()
+    }
+
+    
     init() {
         guard let url = Bundle.main.url(forResource: "data", withExtension: "json") else {
             questions = []
@@ -35,11 +42,10 @@ class ViewModel: ObservableObject {
         
         do {
             let data = try Data(contentsOf: url)
-            questions = try JSONDecoder().decode([QuizQuestion].self, from: data)
+            allQuestionsByCategory = try JSONDecoder().decode([String: [QuizQuestion]].self, from: data)
-            self.selectedAnswers = Array(repeating: nil, count: questions.count)
         } catch {
             print("Fehler beim Laden des Inhalts: \(error)")
-            questions = []
+            allQuestionsByCategory = [:]
         }
     }
     
@@ -51,6 +57,17 @@ class ViewModel: ObservableObject {
         }
     }
     
+    func loadQuestions(for category: String) {
+        selectedCategory = category
+        questions = allQuestionsByCategory[category] ?? []
+        currentQuestionIndex = 0
+        score = 0
+        isQuizFinished = false
+        answeredCount = 0
+        selectedAnswers = Array(repeating: nil, count: questions.count)
+    }
+
+    
     func incrementScore(selectedIndex: Int) {
         if let correct = currentQuestion?.correctAnswer, selectedIndex == correct {
             score += 1

QuizApp/data.json

@@ -1,52 +1,186 @@
-[
+{
+    "Hauptstädte": [
         {
             "question": "Was ist die Hauptstadt von Frankreich?",
-        "answers": ["Rom", "Berlin", "Paris"],
+            "answers": [
+                "Rom",
+                "Berlin",
+                "Paris"
+            ],
             "correctAnswer": 2
         },
         {
             "question": "Was ist die Hauptstadt von Deutschland?",
-        "answers": ["Berlin", "Wien", "Hamburg"],
+            "answers": [
+                "Berlin",
+                "Wien",
+                "Hamburg"
+            ],
             "correctAnswer": 0
         },
         {
             "question": "Was ist die Hauptstadt von Italien?",
-        "answers": ["Rom", "Mailand", "Neapel"],
+            "answers": [
+                "Rom",
+                "Mailand",
+                "Neapel"
+            ],
             "correctAnswer": 0
         },
         {
             "question": "Was ist die Hauptstadt von Spanien?",
-        "answers": ["Barcelona", "Madrid", "Valencia"],
+            "answers": [
+                "Barcelona",
+                "Madrid",
+                "Valencia"
+            ],
             "correctAnswer": 1
         },
         {
             "question": "Was ist die Hauptstadt von Österreich?",
-        "answers": ["Graz", "Salzburg", "Wien"],
+            "answers": [
+                "Graz",
+                "Salzburg",
+                "Wien"
+            ],
             "correctAnswer": 2
         },
         {
             "question": "Was ist die Hauptstadt der Schweiz?",
-        "answers": ["Zürich", "Bern", "Genf"],
+            "answers": [
+                "Zürich",
+                "Bern",
+                "Genf"
+            ],
             "correctAnswer": 1
         },
         {
             "question": "Was ist die Hauptstadt von Portugal?",
-        "answers": ["Lissabon", "Porto", "Faro"],
+            "answers": [
+                "Lissabon",
+                "Porto",
+                "Faro"
+            ],
             "correctAnswer": 0
         },
         {
             "question": "Was ist die Hauptstadt von Belgien?",
-        "answers": ["Brüssel", "Antwerpen", "Brügge"],
+            "answers": [
+                "Brüssel",
+                "Antwerpen",
+                "Brügge"
+            ],
             "correctAnswer": 0
         },
         {
             "question": "Was ist die Hauptstadt von Niederlande?",
-        "answers": ["Rotterdam", "Amsterdam", "Den Haag"],
+            "answers": [
+                "Rotterdam",
+                "Amsterdam",
+                "Den Haag"
+            ],
             "correctAnswer": 1
         },
         {
             "question": "Was ist die Hauptstadt von Polen?",
-        "answers": ["Warschau", "Krakau", "Danzig"],
+            "answers": [
+                "Warschau",
+                "Krakau",
+                "Danzig"
+            ],
             "correctAnswer": 0
         }
+    ],
+    "Mathematik": [
+        {
+            "question": "Was ist 5 + 3?",
+            "answers": [
+                "7",
+                "8",
+                "9"
+            ],
+            "correctAnswer": 1
+        },
+        {
+            "question": "Was ist 12 - 4?",
+            "answers": [
+                "6",
+                "8",
+                "9"
+            ],
+            "correctAnswer": 1
+        },
+        {
+            "question": "Was ist 6 × 7?",
+            "answers": [
+                "42",
+                "36",
+                "48"
+            ],
+            "correctAnswer": 0
+        },
+        {
+            "question": "Was ist 81 ÷ 9?",
+            "answers": [
+                "8",
+                "9",
+                "10"
+            ],
+            "correctAnswer": 1
+        },
+        {
+            "question": "Was ist das Quadrat von 5?",
+            "answers": [
+                "20",
+                "25",
+                "30"
+            ],
+            "correctAnswer": 1
+        },
+        {
+            "question": "Was ist 10 % von 200?",
+            "answers": [
+                "20",
+                "25",
+                "10"
+            ],
+            "correctAnswer": 0
+        },
+        {
+            "question": "Was ergibt 2³?",
+            "answers": [
+                "6",
+                "8",
+                "9"
+            ],
+            "correctAnswer": 1
+        },
+        {
+            "question": "Was ist die Wurzel aus 64?",
+            "answers": [
+                "6",
+                "7",
+                "8"
+            ],
+            "correctAnswer": 2
+        },
+        {
+            "question": "Was ist 3 × (4 + 2)?",
+            "answers": [
+                "18",
+                "20",
+                "12"
+            ],
+            "correctAnswer": 0
+        },
+        {
+            "question": "Wie viel ist 100 ÷ 4?",
+            "answers": [
+                "20",
+                "25",
+                "30"
+            ],
+            "correctAnswer": 1
+        }
     ]
+}