App icon and launch screen in iOS Swift - Build, Publish & Deploy

Build & Publish - App icon and launch screen

Performance Impact

The app icon and launch screen have minimal impact on runtime performance. They do not affect frame rate or battery life during app use. However, a well-optimized launch screen improves perceived performance by showing a quick visual placeholder while the app loads.

Large or complex launch screen images can slightly increase app startup time and memory usage during launch, but this is usually negligible.

Optimization Tips

Use vector assets or appropriately sized images for app icons to avoid scaling and reduce file size.

For launch screens, use simple, static layouts with minimal images. Prefer using Xcode's storyboard launch screen instead of static images for better adaptability and smaller size.

Avoid animations or heavy graphics on the launch screen to keep startup fast and smooth.

App Bundle Size Impact

App icons and launch screen assets contribute to the app bundle size but usually only a few megabytes at most.

Using multiple icon sizes for different devices is required but keep images optimized to avoid unnecessary size increase.

Using a storyboard launch screen instead of multiple static images reduces bundle size and simplifies maintenance.

iOS vs Android Differences

iOS requires app icons in multiple sizes and a launch screen storyboard or images defined in the asset catalog.

Android uses adaptive icons with foreground and background layers and a splash screen defined in XML styles or themes.

iOS launch screens must be static and cannot contain animations, while Android allows simple animations on splash screens.

Code signing and asset catalog management differ between platforms, with iOS requiring strict asset naming and provisioning profiles.

Store Review Guidelines

• App icons must be clear, professional, and not misleading or offensive (Apple Human Interface Guidelines).
• Launch screens should not display branding or promotional content beyond the app's identity.
• Do not use launch screens to show loading progress or splash ads; this can cause rejection.
• Ensure all icon sizes and launch screen assets are included and correctly referenced to avoid app rejection.
• Follow Apple's requirements for icon transparency and shape (no alpha channel in icons except for the App Store icon).

Self-Check Question

Your app takes 5 seconds to load this screen. What's likely wrong?

Possible issues include using large, unoptimized launch screen images or complex layouts causing slow rendering. Also, avoid heavy processing during launch that delays the transition from the launch screen to the app UI.

Key Result

App icons and launch screens have minimal runtime performance impact but affect perceived startup speed and app bundle size. Use optimized images and storyboard launch screens on iOS to ensure fast startup and smooth user experience. Follow Apple's guidelines to avoid app store rejection.

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