NavigationStack in iOS Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ navigation

intermediate

What is the output when navigating with NavigationStack?

Consider this SwiftUI code snippet using NavigationStack. What will the user see after tapping the button labeled "Next"?

iOS Swift

import SwiftUI

struct ContentView: View {
  var body: some View {
    NavigationStack {
      VStack {
        Text("Home Screen")
        NavigationLink("Next", destination: Text("Detail Screen"))
      }
    }
  }
}

A The app shows "Home Screen" but tapping "Next" does nothing.

B The app crashes because NavigationStack requires a NavigationView wrapper.

C The app shows only "Detail Screen" immediately without any navigation.

D The app shows "Home Screen" and a button labeled "Next". Tapping "Next" navigates to a screen showing "Detail Screen".

💡 Hint

Think about how NavigationStack and NavigationLink work together to navigate between views.

NavigationStack is the modern container for navigation in SwiftUI. NavigationLink inside it creates a tappable link that pushes the destination view onto the navigation stack. So tapping "Next" moves from "Home Screen" to "Detail Screen".

❓ ui_behavior

intermediate

What happens if you pop the last view in NavigationStack?

In a NavigationStack with two views pushed, what happens when you pop the last pushed view?

iOS Swift

import SwiftUI

struct ContentView: View {
  @State private var path = [String]()

  var body: some View {
    NavigationStack(path: $path) {
      VStack {
        Button("Go to Detail") {
          path.append("Detail")
        }
      }
      .navigationDestination(for: String.self) { value in
        if value == "Detail" {
          Text("Detail Screen")
        }
      }
    }
  }
}

A Popping the last view returns the user to the root view showing the button "Go to Detail".

B Popping the last view closes the app automatically.

C Popping the last view causes a runtime error because the path becomes empty.

D Popping the last view does nothing; the user stays on the same screen.

💡 Hint

Think about how NavigationStack manages the path array and what an empty path means.

NavigationStack uses the path array to track pushed views. Removing the last element pops the top view and returns to the root view. An empty path means the root view is shown.

❓ lifecycle

advanced

When is the navigationDestination modifier called in NavigationStack?

In SwiftUI's NavigationStack, when does the closure inside navigationDestination(for:) get executed?

iOS Swift

import SwiftUI

struct ContentView: View {
  @State private var path = [Int]()

  var body: some View {
    NavigationStack(path: $path) {
      Button("Go to Number 5") {
        path.append(5)
      }
      .navigationDestination(for: Int.self) { number in
        Text("Number: \(number)")
      }
    }
  }
}

A The closure runs only once when the app launches and never again.

B The closure runs immediately when the view appears, regardless of navigation.

C The closure runs only when the path contains a new Int value and the view needs to display the destination for that value.

D The closure runs every time the user taps anywhere on the screen.

💡 Hint

Consider when SwiftUI needs to show a new screen based on the navigation path.

The navigationDestination closure is called when the NavigationStack needs to show a destination view for a specific data type in the path. It runs when a new value is appended to the path and the destination must be shown.

📝 Syntax

advanced

Which code snippet correctly uses NavigationStack with a path binding?

Choose the correct SwiftUI code that uses NavigationStack with a @State path binding and navigationDestination modifier.

A

struct ContentView: View {
  @State private var path = [String]()
  var body: some View {
    NavigationStack(path: $path) {
      Button("Go") { path.append("Next") }
    }
    .navigationDestination(for: String.self) { Text($0) }
  }
}

B

struct ContentView: View {
  @State private var path = [String]()
  var body: some View {
    NavigationStack(path: $path) {
      Button("Go") { path.append("Next") }
      .navigationDestination(for: String.self) { Text($0) }
    }
  }
}

C

struct ContentView: View {
  @State var path = [String]()
  var body: some View {
    NavigationStack(path: path) {
      Button("Go") { path.append("Next") }
      .navigationDestination(for: String.self) { Text($0) }
    }
  }
}

D

struct ContentView: View {
  @State private var path = [String]()
  var body: some View {
    NavigationStack {
      Button("Go") { path.append("Next") }
      .navigationDestination(for: String.self) { Text($0) }
    }
  }
}

💡 Hint

Remember that NavigationStack's path parameter requires a binding and navigationDestination must be inside the NavigationStack closure.

Option B correctly uses @State private var path with a binding $path passed to NavigationStack. The navigationDestination modifier is inside the NavigationStack closure. Other options either miss the binding, place navigationDestination outside, or omit path binding.

🔧 Debug

expert

Why does this NavigationStack code not navigate on button tap?

This SwiftUI code does not navigate to the detail view when the button is tapped. What is the cause?

iOS Swift

import SwiftUI

struct ContentView: View {
  @State private var path = [String]()

  var body: some View {
    NavigationStack {
      Button("Go to Detail") {
        path.append("Detail")
      }
      .navigationDestination(for: String.self) { value in
        Text("Detail Screen")
      }
    }
  }
}

A The NavigationStack is missing the path binding; it should be NavigationStack(path: $path) to track navigation state.

B The navigationDestination modifier is incorrectly placed outside the NavigationStack closure.

C The path array must be declared as @Binding, not @State.

D The Button label must be a NavigationLink for navigation to work.

💡 Hint

Check how NavigationStack tracks the navigation path and how the path state is connected.

Without passing the binding $path to NavigationStack, it does not track changes to the path array. So appending to path does not trigger navigation. The navigationDestination modifier is correctly placed inside. @State is correct for local state. Button can trigger navigation if path is tracked.