Section

Group rows in lists and inputs in forms using Section with optional headers and footers.

---

Example: Sections in List

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct SectionListDemo: View {
  var body: some View {
List {
  Section(header: Text("Fruits"), footer: Text("End Fruits")) {
    Text("Apple"); Text("Banana")
  }
  Section(header: Text("Veggies")) { Text("Carrot") }
}
  }
}

---

---

Example: Sections in Form

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct SectionFormDemo: View {
  @State private var name = ""
  @State private var notifications = true
  var body: some View {
Form {
  Section(header: Text("Profile"), footer: Text("Shown to others")) {
    TextField("Name", text: $name)
  }
  Section(header: Text("Preferences")) {
    Toggle("Notifications", isOn: $notifications)
  }
}
  }
}

ForEach

Iterate over collections to generate views dynamically using ForEach.

---

ForEach

Render a list of items using ForEach.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct ForEachDemo: View {
  let nums = [1,2,3]
  var body: some View {
VStack {
  ForEach(nums, id: \.self) { n in
    Text("Item \(n)")
  }
}
  }
}

List

Render collections with List using identifiable items.

---

Basic List

Render a list of items using List and ForEach.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct Item: Identifiable { let id: Int; let title: String }

struct ListBasicDemo: View {
  let items = [Item(id: 1, title: "Milk"), Item(id: 2, title: "Bread")]
  var body: some View { List(items) { Text($0.title) } }
}

The example above shows a list of items using List and ForEach.

---

---

Custom rows with ForEach

Render a list of items using List and ForEach.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct Product: Identifiable { let id: Int; let name: String; let price: Double }

struct ListCustomRowsDemo: View {
  let items = [
Product(id: 1, name: "Coffee", price: 2.99),
Product(id: 2, name: "Tea", price: 1.99)
  ]
  var body: some View {
List {
  ForEach(items) { p in
    HStack { Text(p.name); Spacer(); Text(String(format: "$%.2f", p.price)) }
  }
}
  }
}

SwiftUI Lists & Forms

Build data-driven lists with List and collect inputs with Form, rows, and controls.

---

Lists

Render collections with List and ForEach using identifiable items.

Syntax:

• List(items) { Text($0.title) }
• or List { ForEach(items) { ... } }

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct Todo: Identifiable { let id: Int; let title: String }

struct TodoList: View {
  let items = [Todo(id: 1, title: "Buy milk"), Todo(id: 2, title: "Walk dog")]
  var body: some View {
List(items) { t in Text(t.title) }
  }
}

This example displays a simple list of identifiable items using List.

---

---

Forms

Group input controls using Form and built-in rows.

Syntax: Form { Section { TextField(...) } Toggle(...) Stepper(...) }

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct SettingsForm: View {
  @State private var name = ""
  @State private var notifications = true
  @State private var count = 1
  var body: some View {
Form {
  Section(header: Text("Profile")) {
    TextField("Name", text: $name)
  }
  Section(header: Text("Preferences")) {
    Toggle("Notifications", isOn: $notifications)
    Stepper("Count: \(count)", value: $count, in: 1...10)
  }
}
  }
}

Environment (Values)

---

SwiftUI Data Flow @Environment (Values)

Read system- or app-provided values like color scheme and locale using @Environment.

---

Read environment values (color scheme)

Access the current color scheme from the environment and display it in the UI.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct EnvironmentDemo: View {
  @Environment(\.colorScheme) var scheme
  var body: some View {
Text(scheme == .dark ? "Scheme: Dark" : "Scheme: Light")
  .padding()
  }
}

The example above shows a shared object from an ancestor using .environmentObject and consume it in descendants via @EnvironmentObject.

@EnvironmentObject

Provide shared app-wide state from an ancestor view and consume it with @EnvironmentObject.

---

Share app-wide state with @EnvironmentObject

Provide a shared object from an ancestor using .environmentObject and consume it in descendants via @EnvironmentObject.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

final class AppSettings: ObservableObject { @Published var theme = "Light" }

struct Root: View {
  @StateObject private var settings = AppSettings()
  var body: some View {
VStack(spacing: 8) {
  Button("Toggle") { settings.theme = (settings.theme == "Light") ? "Dark" : "Light" }
  Child()
}
.environmentObject(settings)
.padding()
  }
}

struct Child: View {
  @EnvironmentObject var settings: AppSettings
  var body: some View { Text("Theme: \(settings.theme)") }
}

@Binding

Use @Binding to pass a reference to a parent’s state into a child view so updates flow back.

---

Bind child input to parent state

Bind a parent’s state to a child input so edits update the parent value in real time.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct Child: View {
  @Binding var text: String
  var body: some View {
TextField("Enter", text: $text)
  .textFieldStyle(.roundedBorder)
  }
}

struct Parent: View {
  @State private var name = "Kai"
  var body: some View {
VStack {
  Text(name)
  Child(text: $name)
}
.padding()
  }
}

@State

@State is a property wrapper that stores a value locally in a view and updates the UI when the value changes.

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct CounterView: View {
  @State private var count = 0
  var body: some View {
VStack(spacing: 12) {
  Text("Count: \(count)")
  Button("Increment") { count += 1 }
}
.padding()
  }
}

SwiftUI Data Flow

Manage state with @State and @Binding, and share data using ObservableObject, @StateObject, and @EnvironmentObject.

---

@State and @Binding

Use @State for local view state and @Binding to expose it to child views.

Syntax:

• @State private var name = ""
• struct Child { @Binding var name: String }
• pass with Child(name: $name)

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct Child: View {
  @Binding var text: String
  var body: some View {
TextField("Enter", text: $text)
  .textFieldStyle(.roundedBorder)
  }
}

struct Parent: View {
  @State private var text = "Hello"
  var body: some View {
VStack {
  Text(text)
  Child(text: $text)
}
.padding()
  }
}

This example shows a parent exposing local state to a child with @Binding so edits update the parent’s value.

---

---

ObservableObject and StateObject

Share data across views with ObservableObject.

Own it with @StateObject or consume with @ObservedObject.

Syntax:

• class VM: ObservableObject { @Published var count = 0 }
• @StateObject private var vm = VM()
• @ObservedObject var vm: VM

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

class CounterModel: ObservableObject {
  @Published var count = 0
  func increment() { count += 1 }
}

struct ChildView: View {
  @ObservedObject var model: CounterModel
  var body: some View {
HStack {
  Text("Count: \(model.count)")
  Button("Inc") { model.increment() }
}
  }
}

struct ParentView: View {
  @StateObject private var model = CounterModel()
  var body: some View {
VStack(spacing: 12) {
  ChildView(model: model)
}
.padding()
  }
}

The parent owns the model with @StateObject, while the child observes it with @ObservedObject to reflect changes.

---

@EnvironmentObject

Provide shared app state from a root view using .environmentObject(), then consume it in descendants with @EnvironmentObject.

Syntax:

• Root().environmentObject(model)
• @EnvironmentObject var model: Model

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

final class AppSettings: ObservableObject {
  @Published var theme = "Light"
}

struct Root: View {
  @StateObject private var settings = AppSettings()
  var body: some View {
VStack(spacing: 8) {
  Button("Toggle Theme") { settings.theme = (settings.theme == "Light") ? "Dark" : "Light" }
  Child()
}
.environmentObject(settings)
.padding()
  }
}

struct Child: View {
  @EnvironmentObject var settings: AppSettings
  var body: some View { Text("Theme: \(settings.theme)") }
}

SwiftUI Data Flow

Manage state with @State and @Binding, and share data using ObservableObject, @StateObject, and @EnvironmentObject.

---

@State and @Binding

Use @State for local view state and @Binding to expose it to child views.

Syntax:

• @State private var name = ""
• struct Child { @Binding var name: String }
• pass with Child(name: $name)

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

struct Child: View {
  @Binding var text: String
  var body: some View {
TextField("Enter", text: $text)
  .textFieldStyle(.roundedBorder)
  }
}

struct Parent: View {
  @State private var text = "Hello"
  var body: some View {
VStack {
  Text(text)
  Child(text: $text)
}
.padding()
  }
}

This example shows a parent exposing local state to a child with @Binding so edits update the parent’s value.

---

---

ObservableObject and StateObject

Share data across views with ObservableObject.

Own it with @StateObject or consume with @ObservedObject.

Syntax:

• class VM: ObservableObject { @Published var count = 0 }
• @StateObject private var vm = VM()
• @ObservedObject var vm: VM

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

class CounterModel: ObservableObject {
  @Published var count = 0
  func increment() { count += 1 }
}

struct ChildView: View {
  @ObservedObject var model: CounterModel
  var body: some View {
HStack {
  Text("Count: \(model.count)")
  Button("Inc") { model.increment() }
}
  }
}

struct ParentView: View {
  @StateObject private var model = CounterModel()
  var body: some View {
VStack(spacing: 12) {
  ChildView(model: model)
}
.padding()
  }
}

The parent owns the model with @StateObject, while the child observes it with @ObservedObject to reflect changes.

---

@EnvironmentObject

Provide shared app state from a root view using .environmentObject(), then consume it in descendants with @EnvironmentObject.

Syntax:

• Root().environmentObject(model)
• @EnvironmentObject var model: Model

Example

Demo.swift

ContentView.swift

App.swift

import SwiftUI

final class AppSettings: ObservableObject {
  @Published var theme = "Light"
}

struct Root: View {
  @StateObject private var settings = AppSettings()
  var body: some View {
VStack(spacing: 8) {
  Button("Toggle Theme") { settings.theme = (settings.theme == "Light") ? "Dark" : "Light" }
  Child()
}
.environmentObject(settings)
.padding()
  }
}

struct Child: View {
  @EnvironmentObject var settings: AppSettings
  var body: some View { Text("Theme: \(settings.theme)") }
}

The root injects a shared AppSettings; any descendant can read updates via @EnvironmentObject.