Share sheet (UIActivityViewController) in iOS Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens when you present UIActivityViewController without excluding any activity types?

You create and present a UIActivityViewController with a text string to share, but you do not set any excludedActivityTypes. What will the user see?

iOS Swift

let textToShare = "Hello from my app!"
let activityVC = UIActivityViewController(activityItems: [textToShare], applicationActivities: nil)
present(activityVC, animated: true)

A The share sheet shows only the default iOS apps like Messages and Mail, excluding third-party apps.

B The share sheet shows all available sharing options including Messages, Mail, and social media apps installed.

C The share sheet shows no options because excludedActivityTypes is nil.

D The app crashes because excludedActivityTypes must be set before presenting.

💡 Hint

Think about what happens if you don't limit or exclude any sharing options.

If you do not set excludedActivityTypes, the UIActivityViewController shows all available sharing options installed on the device, including third-party apps.

📝 Syntax

intermediate

Which code snippet correctly excludes the AirDrop option from the share sheet?

You want to present a UIActivityViewController but exclude the AirDrop option. Which code snippet does this correctly?

A

activityVC.excludedActivityTypes = [.airDrop]
present(activityVC, animated: true)

B

activityVC.excludedActivityTypes = .airDrop
present(activityVC, animated: true)

C

activityVC.excludedActivityTypes = ["airDrop"]
present(activityVC, animated: true)

D

activityVC.excludedActivityTypes = [UIActivity.ActivityType.airDrop]
present(activityVC, animated: true)

💡 Hint

Check the correct enum type and syntax for excludedActivityTypes.

excludedActivityTypes expects an array of UIActivity.ActivityType values. The correct syntax uses the enum with the full type name.

❓ lifecycle

advanced

What happens if you present UIActivityViewController on iPad without setting popoverPresentationController sourceView?

You present a UIActivityViewController on an iPad but forget to set the popoverPresentationController's sourceView or barButtonItem. What is the expected behavior?

iOS Swift

let text = "Check this out!"
let activityVC = UIActivityViewController(activityItems: [text], applicationActivities: nil)
present(activityVC, animated: true)

A The share sheet appears but with a warning in the console only.

B The share sheet appears centered on the screen without any issues.

C The app crashes with a runtime exception about missing popover sourceView.

D The share sheet does not appear and the app freezes.

💡 Hint

iPad requires a popover anchor for modal presentations like UIActivityViewController.

On iPad, UIActivityViewController must have its popoverPresentationController's sourceView or barButtonItem set, otherwise the app crashes at runtime.

❓ navigation

advanced

How to dismiss UIActivityViewController programmatically after sharing completes?

You want to dismiss the UIActivityViewController automatically after the user finishes sharing. Which approach correctly detects completion and dismisses it?

iOS Swift

let activityVC = UIActivityViewController(activityItems: ["Hello"], applicationActivities: nil)
// What to add here?
present(activityVC, animated: true)

A Set activityVC.completionWithItemsHandler to a closure that calls dismiss(animated: true).

B Set activityVC.delegate = self and implement activityViewControllerDidFinish to dismiss.

C Call dismiss(animated: true) immediately after present(activityVC, animated: true).

D Use NotificationCenter to listen for UIActivityViewControllerDidFinish notification and dismiss.

💡 Hint

UIActivityViewController has a completion handler property for this purpose.

The completionWithItemsHandler closure is called when the user finishes or cancels sharing, allowing you to dismiss the controller programmatically.

🧠 Conceptual

expert

Why should you avoid sharing UIImages directly in UIActivityViewController on iOS 16+?

Starting with iOS 16, sharing UIImages directly in UIActivityViewController can cause issues. What is the recommended approach and why?

A Use file URLs pointing to saved images instead of UIImage objects to avoid memory and performance issues.

B Always convert UIImages to Data before sharing to ensure compatibility with all apps.

C Sharing UIImages directly is recommended for best performance and no issues exist on iOS 16+.

D Wrap UIImages inside a custom UIActivity subclass to fix sharing problems on iOS 16+.

💡 Hint

Think about how large images affect memory and how file URLs can help.

Sharing large UIImages directly can cause memory pressure and crashes. Using file URLs to saved images is more efficient and recommended on iOS 16 and later.