NavigationLink in iOS Swift - Mini App: Build & Ship

Build: Home Screen

This screen shows a list of items. When you tap an item, it navigates to a detail screen showing the item name.

Target UI

Home Screen
----------------
| Item 1       |
| Item 2       |
| Item 3       |
----------------

Tap an item to see details.

Use NavigationLink to navigate from the list to a detail screen.

The detail screen must display the selected item's name.

Use a NavigationView to enable navigation.

Display a list of three items: Item 1, Item 2, Item 3.

Starter Code

iOS Swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        NavigationView {
            List {
                // TODO: Add NavigationLinks here
            }
            .navigationTitle("Home Screen")
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

struct DetailView: View {
    var itemName: String
    var body: some View {
        Text(itemName)
            .font(.largeTitle)
            .navigationTitle("Detail")
    }
}

Task 1

Task 2

Solution

iOS Swift

import SwiftUI

struct ContentView: View {
    let items = ["Item 1", "Item 2", "Item 3"]
    
    var body: some View {
        NavigationView {
            List(items, id: \.self) { item in
                NavigationLink(destination: DetailView(itemName: item)) {
                    Text(item)
                }
            }
            .navigationTitle("Home Screen")
        }
    }
}

struct DetailView: View {
    var itemName: String
    var body: some View {
        Text(itemName)
            .font(.largeTitle)
            .navigationTitle("Detail")
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

We use a NavigationView to enable navigation in the app. Inside it, a List shows three items. Each item is wrapped in a NavigationLink that points to DetailView, passing the item name. When the user taps an item, the app navigates to the detail screen showing the selected item name. The navigationTitle sets the title for each screen.

Final Result

Completed Screen

Home Screen
----------------
| Item 1       |
| Item 2       |
| Item 3       |
----------------

User taps "Item 2"

Detail Screen
----------------
|    Item 2    |
----------------

User taps on an item in the list.

App navigates to the detail screen showing the tapped item's name.

User can swipe back or tap back button to return to Home Screen.

Stretch Goal

Add a button on the Home Screen navigation bar that shows an alert with a welcome message.

💡 Hint

Use the .toolbar modifier with a Button and .alert modifier on the view.

Practice

1. What is the main purpose of NavigationLink in SwiftUI?

easy

A. To display images in a grid layout

B. To create a tappable item that opens a new screen

C. To fetch data from the internet

D. To style text with colors and fonts

Solution

1. Step 1: Understand NavigationLink role

   NavigationLink is used to create tappable items that navigate to another view.

2. Step 2: Compare other options

   Options A, B, and C describe unrelated tasks like styling, fetching data, or layout.

3. Final Answer:

   To create a tappable item that opens a new screen -> Option B

4. Quick Check:

   NavigationLink = tappable navigation [OK]

Hint: NavigationLink always creates tappable navigation items [OK]

Common Mistakes:

• Confusing NavigationLink with styling or data fetching
• Thinking NavigationLink displays images only
• Assuming NavigationLink is for layout purposes

2. Which of the following is the correct syntax to create a NavigationLink with a text label "Next" that opens DetailView()?

easy

A. NavigationLink(destination: Text("Next")) { DetailView() }

B. NavigationLink(destination: Text("Next"), DetailView())

C. NavigationLink { DetailView() } label: { Text("Next") }

D. NavigationLink(destination: DetailView()) { Text("Next") }

Solution

1. Step 1: Recall NavigationLink syntax

   The correct syntax uses NavigationLink(destination: View) { LabelView }.

2. Step 2: Check each option

   NavigationLink(destination: DetailView()) { Text("Next") } matches the correct syntax. NavigationLink(destination: Text("Next"), DetailView()) swaps parameters incorrectly. NavigationLink { DetailView() } label: { Text("Next") } uses a newer syntax and is valid in SwiftUI 3+, so it is also correct. NavigationLink(destination: Text("Next")) { DetailView() } swaps destination and label views wrongly.

3. Final Answer:

   NavigationLink(destination: DetailView()) { Text("Next") } -> Option D

4. Quick Check:

   Correct parameter order = NavigationLink(destination: DetailView()) { Text("Next") } [OK]

Hint: Destination first, label inside closure for NavigationLink [OK]

Common Mistakes:

• Swapping destination and label parameters
• Using incorrect closure syntax
• Passing views in wrong order

3. What will happen when the user taps the text "Go to Profile" in this SwiftUI code?

NavigationView {
  NavigationLink(destination: ProfileView()) {
    Text("Go to Profile")
  }
}

medium

A. The app navigates to ProfileView screen

B. Nothing happens because NavigationView is missing

C. The text changes color but no navigation occurs

D. The app crashes due to missing NavigationLink label

Solution

1. Step 1: Identify NavigationView and NavigationLink usage

   The code wraps NavigationLink inside NavigationView, enabling navigation.

2. Step 2: Understand tap behavior

   Tapping the text triggers navigation to ProfileView as destination is set.

3. Final Answer:

   The app navigates to ProfileView screen -> Option A

4. Quick Check:

   NavigationView + NavigationLink = navigation works [OK]

Hint: NavigationLink inside NavigationView enables screen navigation [OK]

Common Mistakes:

• Forgetting NavigationView disables navigation
• Thinking tap only changes text color
• Assuming app crashes without label

4. Identify the error in this SwiftUI code snippet:

NavigationLink(destination: Text("Details"))
Text("Tap here")

medium

A. Missing braces {} around the label view

B. Destination cannot be a Text view

C. NavigationLink must be inside a NavigationView

D. Text("Tap here") should be inside destination

Solution

1. Step 1: Check NavigationLink syntax

   NavigationLink requires a closure with braces {} for the label view.

2. Step 2: Analyze given code

   The label Text("Tap here") is outside NavigationLink without braces, causing syntax error.

3. Final Answer:

   Missing braces {} around the label view -> Option A

4. Quick Check:

   Label must be inside braces {} [OK]

Hint: Label view must be inside braces {} after NavigationLink [OK]

Common Mistakes:

• Omitting braces for label view
• Thinking destination can't be Text
• Assuming NavigationView is mandatory for syntax

5. You want to create a list of items where each item navigates to a detail screen showing that item's name. Which code correctly uses NavigationLink inside a List to achieve this?

hard

A. ForEach(items) { NavigationLink(destination: DetailView(name: $0)) { Text($0) } }

B. List { NavigationLink(Text(item), destination: DetailView(name: item)) }

C. List(items, id: \.self) { item in NavigationLink(destination: DetailView(name: item)) { Text(item) } }

D. List(items) { item in NavigationLink { Text(item) } destination: { DetailView(name: item) } }

Solution

1. Step 1: Understand List with NavigationLink

   Use List with identifiable items and NavigationLink inside closure for each item.

2. Step 2: Check each option's correctness

   List(items, id: \.self) { item in NavigationLink(destination: DetailView(name: item)) { Text(item) } } correctly uses List with id and NavigationLink with destination and label. List { NavigationLink(Text(item), destination: DetailView(name: item)) } has wrong parameter order. ForEach(items) { NavigationLink(destination: DetailView(name: $0)) { Text($0) } } uses ForEach but misses id and may cause errors. List(items) { item in NavigationLink { Text(item) } destination: { DetailView(name: item) } } uses invalid syntax for NavigationLink.

3. Final Answer:

   List(items, id: \.self) { item in NavigationLink(destination: DetailView(name: item)) { Text(item) } } -> Option C

4. Quick Check:

   List + NavigationLink with destination and label = List(items, id: \.self) { item in NavigationLink(destination: DetailView(name: item)) { Text(item) } } [OK]

Hint: Use List with id and NavigationLink inside closure [OK]

Common Mistakes:

• Wrong parameter order in NavigationLink
• Missing id in List or ForEach
• Using invalid NavigationLink syntax