SwiftPlaybook.txt

# SwiftUI Coding Solutions Playbook
Author: Anthropic's AI Claude

This playbook covers some of the most common SwiftUI patterns and solutions. 

## Table of Contents
1. Structs
2. Classes
3. Functions
4. Views
5. State and Binding
6. ObservableObject
7. Environment Objects
8. View Modifiers
9. Lists and Navigation
10. Gestures

## 1. Structs

Structs are value types and are commonly used in SwiftUI for model data.

```swift
struct User {
    let id: UUID
    var name: String
    var age: Int
}

// Usage
let user = User(id: UUID(), name: "John Doe", age: 30)
```

## 2. Classes

Classes are reference types and are used when you need inheritance or reference semantics.

```swift
class UserManager {
    static let shared = UserManager()
    private init() {}
    
    var currentUser: User?
    
    func login(user: User) {
        currentUser = user
    }
    
    func logout() {
        currentUser = nil
    }
}
```

## 3. Functions

Functions in Swift can be standalone or part of a type.

```swift
func greet(_ name: String) -> String {
    return "Hello, \(name)!"
}

// Usage
let greeting = greet("Alice")
```

## 4. Views

Views are the building blocks of your SwiftUI interface.

```swift
struct ContentView: View {
    var body: some View {
        VStack {
            Text("Welcome to SwiftUI")
                .font(.title)
            Button("Tap me") {
                print("Button tapped")
            }
        }
    }
}
```

## 5. State and Binding

`@State` is used for local state, while `@Binding` allows you to pass mutable state to child views.

```swift
struct CounterView: View {
    @State private var count = 0
    
    var body: some View {
        VStack {
            Text("Count: \(count)")
            Button("Increment") {
                count += 1
            }
            CounterButtonView(count: $count)
        }
    }
}

struct CounterButtonView: View {
    @Binding var count: Int
    
    var body: some View {
        Button("Decrement") {
            count -= 1
        }
    }
}
```

## 6. ObservableObject

`ObservableObject` is used for more complex state management across multiple views.

```swift
class UserViewModel: ObservableObject {
    @Published var user: User?
    
    func fetchUser() {
        // Simulating an API call
        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
            self.user = User(id: UUID(), name: "Jane Doe", age: 28)
        }
    }
}

struct UserView: View {
    @StateObject private var viewModel = UserViewModel()
    
    var body: some View {
        VStack {
            if let user = viewModel.user {
                Text("Name: \(user.name)")
                Text("Age: \(user.age)")
            } else {
                Text("Loading...")
            }
        }
        .onAppear {
            viewModel.fetchUser()
        }
    }
}
```

## 7. Environment Objects

Environment objects allow you to share data throughout your app's view hierarchy.

```swift
class AppSettings: ObservableObject {
    @Published var isDarkMode = false
}

@main
struct MyApp: App {
    @StateObject private var appSettings = AppSettings()
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(appSettings)
        }
    }
}

struct ContentView: View {
    @EnvironmentObject var appSettings: AppSettings
    
    var body: some View {
        Toggle("Dark Mode", isOn: $appSettings.isDarkMode)
    }
}
```

## 8. View Modifiers

Custom view modifiers allow you to encapsulate common view modifications.

```swift
struct RoundedBackground: ViewModifier {
    func body(content: Content) -> some View {
        content
            .padding()
            .background(Color.blue)
            .cornerRadius(10)
    }
}

extension View {
    func roundedBackground() -> some View {
        self.modifier(RoundedBackground())
    }
}

// Usage
Text("Hello, World!")
    .roundedBackground()
```

## 9. Lists and Navigation

SwiftUI makes it easy to create lists and navigation hierarchies.

```swift
struct Item: Identifiable {
    let id = UUID()
    let name: String
}

struct ListView: View {
    let items = [Item(name: "Apple"), Item(name: "Banana"), Item(name: "Cherry")]
    
    var body: some View {
        NavigationView {
            List(items) { item in
                NavigationLink(destination: DetailView(item: item)) {
                    Text(item.name)
                }
            }
            .navigationTitle("Fruits")
        }
    }
}

struct DetailView: View {
    let item: Item
    
    var body: some View {
        Text("Details for \(item.name)")
    }
}
```

## 10. Gestures

SwiftUI provides a declarative way to handle gestures.

```swift
struct GestureView: View {
    @State private var offset = CGSize.zero
    
    var body: some View {
        Circle()
            .fill(Color.blue)
            .frame(width: 100, height: 100)
            .offset(offset)
            .gesture(
                DragGesture()
                    .onChanged { gesture in
                        offset = gesture.translation
                    }
                    .onEnded { _ in
                        withAnimation {
                            offset = .zero
                        }
                    }
            )
    }
}
```