Share sheet (UIActivityViewController) in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a share sheet with a text message.

iOS Swift

let textToShare = "Hello from my app!"
let activityVC = UIActivityViewController(activityItems: [[1]], applicationActivities: nil)

Drag options to blanks, or click blank then click option'

Anil

Bself

CtextToShare

Dview

Attempts:

3 left

💡 Hint

Common Mistakes

Passing self or view instead of the text variable.

Not putting the item inside an array.

The share sheet needs the content to share inside an array. Here, we share the text stored in textToShare.

2fill in blank

medium

Complete the code to present the share sheet from the current view controller.

iOS Swift

present(activityVC, animated: [1], completion: nil)

Drag options to blanks, or click blank then click option'

Atrue

B0

Cnil

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Passing false disables animation and is less user-friendly.

Passing nil or 0 causes errors.

The share sheet should be presented with animation, so pass true for the animated parameter.

3fill in blank

hard

Fix the error in the code to avoid a crash on iPad by setting the popoverPresentationController's sourceView.

iOS Swift

if let popover = activityVC.popoverPresentationController {
    popover.sourceView = [1]
}

Drag options to blanks, or click blank then click option'

AUIApplication.shared

Bnil

CactivityVC

Dself.view

Attempts:

3 left

💡 Hint

Common Mistakes

Setting sourceView to nil causes a crash on iPad.

Using activityVC or UIApplication.shared is incorrect.

On iPad, the share sheet must have a sourceView for the popover. Setting it to self.view fixes the crash.

4fill in blank

hard

Fill both blanks to share an image named "photo.png" from the app bundle.

iOS Swift

if let image = UIImage(named: [1]) {
    let activityVC = UIActivityViewController(activityItems: [[2]], applicationActivities: nil)
}

Drag options to blanks, or click blank then click option'

A"photo.png"

B"photo"

Cimage

Dself

Attempts:

3 left

💡 Hint

Common Mistakes

Including the file extension in the image name.

Passing the string instead of the image variable to activityItems.

UIImage(named:) expects the image name without extension. The activityItems array needs the image variable.

5fill in blank

hard

Fill all three blanks to share a URL and exclude the AirDrop activity from the share sheet.

iOS Swift

if let url = URL(string: [1]) {
    let activityVC = UIActivityViewController(activityItems: [url], applicationActivities: nil)
    activityVC.excludedActivityTypes = [[2]]
    present(activityVC, animated: [3], completion: nil)
}

Drag options to blanks, or click blank then click option'

A"https://example.com"

B.airDrop

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting the URL string.

Using wrong activity type to exclude.

Passing false to animated parameter.

The URL string must be quoted. To exclude AirDrop, use .airDrop. Present the share sheet with animation true.

Practice

1. What is the main purpose of UIActivityViewController in an iOS app?

easy

A. To manage app settings

B. To present a share sheet allowing users to share content

C. To create a custom navigation bar

D. To handle background tasks

Solution

1. Step 1: Understand the role of UIActivityViewController

   UIActivityViewController is designed to present a share sheet for sharing content.

2. Step 2: Compare with other options

   Options A, B, and D relate to different app functions not handled by UIActivityViewController.

3. Final Answer:

   To present a share sheet allowing users to share content -> Option B

4. Quick Check:

   Share sheet = UIActivityViewController [OK]

Hint: UIActivityViewController always shows sharing options [OK]

Common Mistakes:

• Confusing UIActivityViewController with navigation or settings controllers
• Thinking it manages background tasks
• Assuming it customizes UI elements beyond sharing

2. Which of the following is the correct way to initialize a UIActivityViewController with a text string to share?

easy

A. UIActivityViewController(activityItems: ["Hello World"], applicationActivities: nil)

B. UIActivityViewController(items: "Hello World")

C. UIActivityViewController(shareItems: ["Hello World"])

D. UIActivityViewController(content: "Hello World")

Solution

1. Step 1: Recall the initializer signature

   The correct initializer is UIActivityViewController(activityItems: [Any], applicationActivities: [UIActivity]?).

2. Step 2: Match the correct syntax

   UIActivityViewController(activityItems: ["Hello World"], applicationActivities: nil) matches the correct syntax with an array of items and nil for activities.

3. Final Answer:

   UIActivityViewController(activityItems: ["Hello World"], applicationActivities: nil) -> Option A

4. Quick Check:

   Initializer uses activityItems array [OK]

Hint: Use activityItems array to pass share content [OK]

Common Mistakes:

• Passing a single string instead of an array
• Using wrong parameter names like items or shareItems
• Omitting applicationActivities parameter

3. Given the code snippet below, what will happen when the button is tapped?

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

medium

A. The text is copied automatically to clipboard

B. The app crashes due to missing delegate

C. A share sheet appears allowing the user to share the text

D. Nothing happens because the share sheet is not presented

Solution

1. Step 1: Analyze the code behavior

   The code creates a UIActivityViewController with a text item and presents it modally.

2. Step 2: Understand UIActivityViewController presentation

   Presenting it modally shows the share sheet with sharing options for the text.

3. Final Answer:

   A share sheet appears allowing the user to share the text -> Option C

4. Quick Check:

   Presenting UIActivityViewController shows share sheet [OK]

Hint: Presenting UIActivityViewController shows share sheet [OK]

Common Mistakes:

• Assuming delegate is required to present share sheet
• Thinking share sheet appears automatically without present()
• Confusing share sheet with clipboard copy

4. Identify the error in the following code that tries to present a share sheet:

let image = UIImage(named: "photo.png")
let activityVC = UIActivityViewController(activityItems: [image], applicationActivities: nil)
present(activityVC, animated: true)

medium

A. present() must be called on the activityVC instance

B. UIActivityViewController requires a delegate to present

C. The activityItems parameter must be a single item, not an array

D. UIImage named "photo.png" may be nil

Solution

1. Step 1: Check UIImage initialization

   UIImage(named:) returns an optional and may be nil if the image is missing.

2. Step 2: Understand impact on activityItems

   Passing nil in activityItems array results in no shareable content.

3. Final Answer:

   UIImage named "photo.png" may be nil -> Option D

4. Quick Check:

   UIImage(named:) can be nil if image missing [OK]

Hint: Always unwrap UIImage before sharing [OK]

Common Mistakes:

• Assuming delegate is required for UIActivityViewController
• Passing single item instead of array to activityItems
• Calling present() on wrong object

5. You want to share both a URL and a text message using UIActivityViewController. Which code snippet correctly sets this up and presents the share sheet?

hard

A. let url = URL(string: "https://example.com")!
let message = "Check this out!"
let activityVC = UIActivityViewController(activityItems: [url, message], applicationActivities: nil)
present(activityVC, animated: true)

B. let url = URL(string: "https://example.com")
let message = "Check this out!"
let activityVC = UIActivityViewController(activityItems: url, applicationActivities: message)
present(activityVC, animated: true)

C. let url = URL(string: "https://example.com")!
let message = "Check this out!"
let activityVC = UIActivityViewController(items: [url, message])
present(activityVC, animated: true)

D. let url = URL(string: "https://example.com")!
let message = "Check this out!"
let activityVC = UIActivityViewController(activityItems: [message], applicationActivities: [url])
present(activityVC, animated: true)

Solution

1. Step 1: Verify correct initializer usage

   UIActivityViewController requires activityItems as an array of items to share and applicationActivities as optional custom activities.

2. Step 2: Check each option's parameters

   let url = URL(string: "https://example.com")! let message = "Check this out!" let activityVC = UIActivityViewController(activityItems: [url, message], applicationActivities: nil) present(activityVC, animated: true) correctly passes an array with URL and text, and nil for applicationActivities.

3. Step 3: Confirm safe URL unwrapping

   let url = URL(string: "https://example.com")! let message = "Check this out!" let activityVC = UIActivityViewController(activityItems: [url, message], applicationActivities: nil) present(activityVC, animated: true) force unwraps URL safely assuming it exists, which is common in examples.

4. Final Answer:

   let url = URL(string: "https://example.com")! let message = "Check this out!" let activityVC = UIActivityViewController(activityItems: [url, message], applicationActivities: nil) present(activityVC, animated: true) -> Option A

5. Quick Check:

   Pass array of items to activityItems [OK]

Hint: Pass all share items in activityItems array [OK]

Common Mistakes:

• Passing items or applicationActivities incorrectly
• Not using an array for activityItems
• Confusing applicationActivities with share content