App icon and launch screen in iOS Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens if the launch screen storyboard is missing?

In an iOS app, if the launch screen storyboard file is not set or missing, what will the user see when the app starts?

A A white screen until the app finishes loading

B The app's main interface immediately without any delay

C A black screen until the app finishes loading

D The app crashes on launch

💡 Hint

Think about the default background color shown by iOS when no launch screen is provided.

If the launch screen storyboard is missing, iOS shows a white screen by default while the app loads. It does not crash or show the main interface immediately.

🧠 Conceptual

intermediate

Why use an asset catalog for app icons?

Why is it recommended to use an asset catalog to manage app icons in an iOS project?

A Because asset catalogs automatically manage all required icon sizes and organize them efficiently

B Because asset catalogs allow you to write code to change icons dynamically

C Because asset catalogs reduce the app size by compressing icons at runtime

D Because asset catalogs are required to display icons only on iPads

💡 Hint

Think about how Xcode handles multiple icon sizes for different devices.

Asset catalogs help organize all icon sizes in one place and Xcode uses them to provide the correct icon for each device automatically.

📝 Syntax

advanced

Which Info.plist key sets the launch screen storyboard?

In the Info.plist file, which key correctly specifies the launch screen storyboard file name?

A "UIStoryboardLaunchName" with the storyboard file name as value

B "LaunchScreenFile" with the storyboard file name as value

C "CFBundleLaunchScreen" with the storyboard file name as value

D "UILaunchStoryboardName" with the storyboard file name as value

💡 Hint

Check the official Apple documentation for the exact key name.

The correct key to specify the launch screen storyboard in Info.plist is "UILaunchStoryboardName".

❓ lifecycle

advanced

When is the launch screen displayed during app startup?

At what point during the iOS app startup lifecycle is the launch screen shown to the user?

A After the app delegate's application(_:didFinishLaunchingWithOptions:) method completes

B Only after the first view controller is fully loaded

C While the app is loading and before the main interface is ready

D Before the app process starts running any code

💡 Hint

Think about what the launch screen is meant to mask.

The launch screen is displayed while the app is loading and before the main interface is ready, providing a smooth transition.

🔧 Debug

expert

Why does the app icon not update after adding new images?

You added new app icon images to the asset catalog and set them correctly, but the app icon on the device still shows the old icon. What is the most likely cause?

A The asset catalog was not included in the build target

B The app needs to be deleted and reinstalled to clear the icon cache

C The Info.plist does not reference the asset catalog for icons

D The device does not support the new icon sizes

💡 Hint

Think about how iOS caches app icons on devices.

iOS caches app icons, so after updating icons, deleting and reinstalling the app clears the cache and shows the new icon.

Practice

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

easy

A. To display the app's settings menu

B. To represent the app on the home screen and App Store

C. To show a loading animation when the app starts

D. To provide user notifications

Solution

1. Step 1: Understand what an app icon is

   The app icon is the image users see on their device's home screen and in the App Store.

2. Step 2: Identify the purpose of the app icon

   It visually represents the app so users can recognize and open it easily.

3. Final Answer:

   To represent the app on the home screen and App Store -> Option B

4. Quick Check:

   App icon = app representation [OK]

Hint: App icon shows your app's picture on the device [OK]

Common Mistakes:

• Confusing app icon with launch screen
• Thinking app icon controls notifications
• Believing app icon shows loading animations

2. Which file or folder is used to set the app icon images in an Xcode iOS project?

easy

A. Assets.xcassets/AppIcon.appiconset

B. Main.storyboard

C. Info.plist

D. LaunchScreen.storyboard

Solution

1. Step 1: Identify where app icons are stored

   App icons are placed inside the Assets.xcassets folder, specifically in the AppIcon.appiconset.

2. Step 2: Differentiate from other files

   LaunchScreen.storyboard is for launch screens, Info.plist holds app settings, and Main.storyboard is for UI layout.

3. Final Answer:

   Assets.xcassets/AppIcon.appiconset -> Option A

4. Quick Check:

   App icons = Assets.xcassets/AppIcon.appiconset [OK]

Hint: App icons live in Assets.xcassets, not storyboard files [OK]

Common Mistakes:

• Choosing storyboard files for app icons
• Confusing Info.plist with icon storage
• Not knowing Assets.xcassets purpose

3. Given the following code snippet in an iOS app project, what will the launch screen display when the app starts?

/* LaunchScreen.storyboard contains a centered image named 'LaunchImage' */
// No code changes to launch screen

medium

A. The image named 'LaunchImage' centered on the screen

B. A blank white screen

C. The app icon displayed full screen

D. An error because launch screen needs code

Solution

1. Step 1: Understand launch screen storyboard setup

   The LaunchScreen.storyboard has a centered image named 'LaunchImage'. This storyboard is shown while the app loads.

2. Step 2: Predict what appears on launch

   Since the storyboard shows the image centered, the launch screen will display that image centered on the screen.

3. Final Answer:

   The image named 'LaunchImage' centered on the screen -> Option A

4. Quick Check:

   Launch screen storyboard shows its content [OK]

Hint: Launch screen shows storyboard content, no code needed [OK]

Common Mistakes:

• Thinking launch screen shows app icon automatically
• Assuming launch screen is blank without code
• Believing launch screen requires Swift code

4. You set a launch screen storyboard but when running the app, the launch screen shows a black screen instead of your design. What is the most likely cause?

medium

A. The app's Info.plist is missing

B. The app icon images are missing

C. The storyboard file has syntax errors in Swift code

D. The launch screen storyboard is not assigned in the project settings

Solution

1. Step 1: Check launch screen assignment

   If the launch screen storyboard is not set in the project settings under 'Launch Screen File', the app shows a black screen on launch.

2. Step 2: Rule out other causes

   Missing app icons or Info.plist issues do not cause black launch screens. Storyboards do not contain Swift code, so no syntax errors apply.

3. Final Answer:

   The launch screen storyboard is not assigned in the project settings -> Option D

4. Quick Check:

   Launch screen file must be set in project [OK]

Hint: Always assign launch storyboard in project settings [OK]

Common Mistakes:

• Confusing app icon issues with launch screen problems
• Expecting Swift code in storyboard files
• Ignoring project settings for launch screen

5. You want your app to show a launch screen with a background color and a centered logo image. Which steps correctly set this up in Xcode?

hard

A. Write Swift code in AppDelegate to display the image and background color on launch

B. Add the logo image to Assets.xcassets and set it as the app icon; no storyboard needed

C. Create a LaunchScreen.storyboard with a view colored as background and an image view centered; assign this storyboard in project settings

D. Set the background color and image in Info.plist under launch screen keys

Solution

1. Step 1: Design launch screen in storyboard

   Create a LaunchScreen.storyboard file with a view that has the desired background color and add an image view centered with the logo image.

2. Step 2: Assign launch screen storyboard in project

   In Xcode project settings, set the 'Launch Screen File' to this storyboard so the system shows it on app launch.

3. Final Answer:

   Create a LaunchScreen.storyboard with a view colored as background and an image view centered; assign this storyboard in project settings -> Option C

4. Quick Check:

   Launch screen = storyboard design + project assignment [OK]

Hint: Use storyboard for launch screen design, assign in settings [OK]

Common Mistakes:

• Trying to set launch screen via Info.plist
• Confusing app icon with launch screen setup
• Attempting to use Swift code for launch screen UI