Deep linking in iOS Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens when the app receives a deep link URL?

Consider an iOS app configured to handle deep links. When the app receives a URL like myapp://profile/123, what is the expected behavior?

A The app opens and navigates to the profile screen showing user with ID 123.

B The app crashes because the URL scheme is not recognized.

C The app opens but stays on the home screen without navigation.

D The app opens a web browser to load the URL externally.

💡 Hint

Deep links allow apps to open specific screens directly.

Deep linking lets the app open a specific screen based on the URL path. Here, the app should navigate to the profile screen for user 123.

📝 Syntax

intermediate

Which Swift method handles incoming deep link URLs in the app delegate?

In iOS Swift apps, which method is called when the app is asked to open a URL via deep linking?

A func applicationWillTerminate(_ application: UIApplication)

B func applicationDidBecomeActive(_ application: UIApplication)

C func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool

D func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool

💡 Hint

This method receives the URL and options when opening a URL.

The method with signature application(_:open:options:) is called to handle URLs opened by the app, including deep links.

❓ lifecycle

advanced

What happens if the app is not running and a deep link is opened?

If the user taps a deep link URL and the app is not running at all, what is the correct sequence of events in iOS?

A The app launches and immediately crashes due to missing URL handling.

B The app launches, but the URL is ignored because the app was not running.

C The app launches, <code>didFinishLaunchingWithOptions</code> is called with the URL info, then <code>application(_:open:options:)</code> is called.

D The app launches and only <code>applicationDidBecomeActive</code> is called without URL info.

💡 Hint

The launch options contain the URL when the app starts from a deep link.

When launched from a deep link, didFinishLaunchingWithOptions receives the URL in launch options, then the URL handling method is called.

🔧 Debug

advanced

Why does this deep link handler fail to navigate?

Given this Swift code snippet in the app delegate handling a deep link URL:

func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
  if url.scheme == "myapp" {
    if url.host == "profile" {
      let userId = url.lastPathComponent
      navigateToProfile(userId: userId)
      return true
    }
  }
  return false
}

Why might the navigation not work as expected?

A The method <code>navigateToProfile</code> is not defined in the app delegate.

B The <code>url.lastPathComponent</code> is empty because the URL path is missing or malformed.

C The <code>url.scheme</code> is incorrect and does not match the app's scheme.

D The method returns false, so the system ignores the URL.

💡 Hint

Check how the URL path is parsed for the user ID.

If the URL does not have a path component after the host, lastPathComponent will be empty, so navigation lacks the user ID.

🧠 Conceptual

expert

How does Universal Links improve deep linking on iOS?

Which statement best describes the advantage of Universal Links over custom URL schemes for deep linking on iOS?

A Universal Links open the app directly without showing a prompt and fallback to the website if the app is not installed.

B Universal Links require the user to manually copy and paste URLs into the app.

C Universal Links only work when the app is already running in the background.

D Universal Links force the app to open a web view instead of native screens.

💡 Hint

Universal Links use standard web URLs and improve user experience.

Universal Links use standard HTTPS URLs that open the app directly if installed, or fallback to the website if not, without prompts.