App Thinning

App Thinning is a set of technologies introduced by Apple that optimize the delivery of iOS apps by ensuring each device downloads only the resources it actually needs. Instead of distributing a universal binary containing assets for every supported device, App Thinning creates tailored variants that reduce download size, installation footprint, and storage usage.

Three Components of App Thinning

App Thinning consists of three distinct technologies. Slicing creates device-specific app variants at the App Store level, including only the executable architecture, GPU resources, and image assets appropriate for the target device. Bitcode allows Apple to recompile and optimize your app for specific hardware after submission, though Apple deprecated Bitcode in Xcode 14. On-Demand Resources let developers tag certain assets to be downloaded only when needed and purged when storage is low, which is especially useful for games and content-heavy apps.

Why App Size Matters for ASO

App download size has a direct impact on conversion rates. Apple enforces a 200 MB cellular download limit, and apps exceeding this threshold require Wi-Fi, which creates friction that reduces impulse downloads. Smaller apps also install faster, leading to quicker first-launch experiences and lower abandonment rates. Users with limited storage are more likely to delete large apps, hurting retention metrics. By leveraging App Thinning effectively, developers can keep their app’s download size below critical thresholds, improving both conversion rates and long-term retention in competitive App Store categories.