Tips to Reduce iOS App Size Without Compromising Performance

Recent Apple App Store guidelines emphasize keeping app sizes minimal. According to Statista, over 1.8 million iOS apps compete for user attention in 2025. Yet, 65% of users abandon apps due to long download times or insufficient device storage. Developers involved in iOS Application Development must now focus on optimizing app size without reducing functionality or speed.

Reducing iOS app size not only helps with user retention but also boosts App Store rankings and install rates. This article outlines proven technical tips for minimizing iOS app size without sacrificing performance or user experience. Whether you’re building a game or a productivity tool, these insights apply universally across most iOS development projects.

Why App Size Matters in iOS Application Development

Before exploring techniques, it’s vital to understand the implications of app size:

• App Store Over-the-Air (OTA) Download Limits: Apps larger than 200 MB require Wi-Fi for download. This affects users on mobile networks.

• Slower Install Times: Large apps take longer to download and install, increasing drop-off rates.

• Storage Management: Users regularly delete apps that consume too much space.

• Update Resistance: Larger apps receive fewer updates due to the download size barrier.

Keeping app size low improves accessibility, especially in emerging markets where devices have limited storage.

1. Use Asset Catalogs Efficiently

Asset catalogs group images and other media under a single file system that iOS can manage efficiently.

Tips:

• Avoid using high-resolution images unless necessary.

• Use vector images (PDF or SVG) for UI assets that scale without increasing file size.

• Apply on-demand resources for optional features like tutorial videos or skins.

Example: Instead of bundling all tutorial videos in the app, load them as on-demand resources only when required.

2. Compress Image and Audio Files

Unoptimized media assets often account for more than 50% of app size.

Best practices:

• Use modern image formats like HEIC instead of PNG or JPEG.

• Compress audio using AAC format.

• Avoid 24-bit audio for simple UI feedback sounds.

Real-world case: A social media app reduced its initial download size by 42% just by converting JPEGs to HEIC and switching to AAC audio files.

3. Enable Bitcode and Dead Code Stripping

Bitcode allows Apple to recompile the app after submission for further optimization.

Steps to enable:

• In Xcode, go to Build Settings > Enable Bitcode > Set to Yes.

• Also enable Dead Code Stripping to remove unused methods and functions.

Benefits:

• Optimized binary at compile time.

• Removes unused logic and test methods.

This is particularly useful in large projects with multiple frameworks and legacy components.

4. Split App into Dynamic Frameworks and Modules

Monolithic codebases inflate app binaries. Modularizing helps reduce size and improves maintainability.

Advantages:

• Only load necessary modules during runtime.

• Reuse modules across multiple apps without bundling them again.

Use case: A ride-sharing app using a single shared map module across rider, driver, and admin apps saved over 10 MB per install.

5. Use App Thinning (Slicing, Bitcode, and On-Demand Resources)

App Thinning automatically tailors the app to the target device.

Slicing

Generates a device-specific app package (e.g., iPhone 14 Pro Max only downloads its needed assets).

Bitcode

Allows re-optimization by Apple servers when new architectures are supported.

On-Demand Resources

Downloads parts of the app when the user needs them.

Example: A game can offer level downloads as on-demand, instead of pre-installing all levels.

6. Optimize Third-Party Libraries and SDKs

Many third-party libraries are bulky and unused in full.

Tips:

• Choose lightweight alternatives (e.g., use Alamofire over heavy networking SDKs).

• Import only required modules instead of entire SDKs.

• Remove unnecessary demo or sample files included in third-party packages.

Real-world case: Replacing Firebase Analytics with a leaner custom event tracker reduced app size by 3.8 MB.

7. Use Swift Package Manager Over CocoaPods

CocoaPods often includes unnecessary dependencies and bloats the app bundle.

Why Swift Package Manager (SPM) is better:

• Integrated in Xcode.

• Does not add static files into the app.

• Lightweight and more secure.

Pro tip: Migrate libraries from CocoaPods to SPM where possible, especially for open-source utilities.

8. Minimize Embedded Fonts and Localized Strings

Fonts and localization files add unnecessary weight when not handled carefully.

How to optimize:

• Use system fonts where feasible.

• Only include languages required for your target markets.

• Compress .strings files and remove developer comments.

Tip: Use .ttf fonts instead of .otf, which are generally larger.

9. Limit Use of Custom Animations and Media

Custom animations created in tools like Lottie or After Effects can be bulky.

Alternatives:

• Use iOS-native Core Animation and UIKit transitions.

• Replace animated PNG sequences with vector-based Lottie animations only when needed.

• Offload optional media content to cloud storage.

10. Profile App Size with Xcode Tools

Apple offers built-in tools to monitor and reduce app size.

Tools to use:

• Xcode Size Report: Analyzes app binary size and identifies large sections.

• App Store Connect Metrics: Offers real device statistics and install data.

• Instruments Tool: Helps track memory usage and heavy assets.

Checklist:

• Run xcrun bitcode-build-tool to simulate App Store processing.

• Review .ipa content before submission.

11. Remove Debug Symbols and Logs in Production Builds

Debug symbols and verbose logs can inflate your release binary.

Steps:

• Disable DEBUG flags in production scheme.

• Strip .dSYM files unless needed for crash reporting.

• Remove print() and NSLog() statements.

12. Prioritize Clean Code Architecture

Clean architecture ensures only relevant classes and logic stay in the final build.

How to maintain it:

• Use MVVM or VIPER to isolate reusable logic.

• Remove deprecated classes.

• Regularly audit unused controllers and views.

Real-world tip: HashStudioz’s internal iOS Application Development team reduced a client’s app size by 12 MB just through modular refactoring and pruning legacy code.

13. Use Lightweight JSON or Protobuf Instead of XML

When handling API responses or embedded data:

• Avoid XML, which is verbose.

• Use compact data formats like Protobuf or compressed JSON.

• Gzip network responses to reduce payload size.

14. Reduce Use of Storyboards

Large storyboards consume memory and storage.

Best approach:

• Break up into smaller storyboards or use XIB files.

• Consider SwiftUI for more compact UIs.

Summary Table: Key Methods to Reduce iOS App Size

Conclusion

Reducing iOS app size is not about cutting corners. It’s about optimizing every layer — from code and assets to build settings and architecture. Applying these best practices leads to faster downloads, better user experience, and wider reach, especially in bandwidth-constrained environments.

Developers involved in iOS Application Development should prioritize these optimizations from the early stages of development. It results in faster time to market, fewer user complaints, and better App Store performance.

Remember: every megabyte saved is a better chance at user retention.