Usipov/iOS-Performance-Optimization

This project contains resources on how you can optimize your iOS application performance

iOS-Performance-Optimization

This project contains foundation knowledge and highly recommended resources on optimizing your iOS application performance. Contributions are welcome 👋

Table of Contents

• Reduce App Size
• Reduce Build time
• App Launch time
• App Runtime
• App Hang
• Memory usage
• CI

Reduce App Size

Foundation knowledge

• Understand iOS App Size by Emerge
• Understand static framework & dynamic framework by Emerge
• Basic optimization to reduce app size by Apple
• Advance optimization to reduce app size by Apple
• Reducing app size by Apple
• Strip Binary Simple
• Xcode build time optimization
• Are Android apps THAT much smaller than iOS? by Emerge

Tools

• Emerge Tool size Analysis
• Periphery - Static analysis - Unused code detection
• FengNiao - Unused image detection
• Reaper by Emerge: Dynamic analysis for Unused code

Real-life example

• How Uber Deals with Large iOS App Size
• How 7 iOS Apps Could Save You 500MB of Storage by Emerge
• Spotify
• Make Your iOS App Smaller with Dynamic Frameworks
• Manage Image Resources
• Duolingo remove 10000 lines of unused code by using Reaper

Reduce Build time

Foundation knowledge

• Clean build vs. Incremental build
• Swift Compiler Performance by Apple
• Understanding Swift Performance by Apple: Understand how ARC works and how it impacts your app's performance
• Performance of value type by Swiftrocks

Tools

• Xcode Build time Rendering
• XCMetrics
• Tuist
• Bazel
• Cocoapod binary cache by Grab
• Build time analyzer: Measure the time Xcode takes to compile every funcs

Real-life example

• Grab
• Gojek
• Tokopedia
• Building faster by Apple
• Caching SPM dependencies in CI

App launch time

Foundation knowledge

• About the app launch sequence by Apple
• Cold launch vs Warm launch: Apple
• Dynamic Linker vs Static Linker
• Mach-O
• Dyld

Tools

• Xcode Instruments

Real-life example

• Apple
• Uber
• Facebook Dynamic Loading
• How Door Dash Reduced iOS App Launch Time by 60%
• Why Swift Reference Types Are Bad for App Startup Time - Emerge

App Runtime

Foundation Knowledge

• Thread explosion by SwiftSenpai
• Making efficient use of the libdispatch (GCD) by Apple engineer

Tools

• os signpost
• ETTrace

App Hang

Foundation Knowledge

• Understanding hangs in your app
• Understand and eliminate hangs from your app

Tools

• Track down hangs with Xcode and on-device detection: track hangs during pre-release testing, show you how to identify issues in release builds using the Xcode Organizer
• Analyzing responsiveness issues in your shipping app

Memory Usage

Foundation Knowledge

• You don't always need weak self
• Nested closure weak self
• Detect Unused code using Memory graph debugger
• Automating Memory Leak Detection with CI Integration

Tools

• Memory Leaks Check: A tool for detecting memory leak in CI

Real life examples

• The Memory Leak: An Xcode Detective Story by Emerge

CI

Examples

• Performance testing on CI
• Selective testing