sond813

Parts of the binary on the App Store are encrypted so we can only get limited information from it, but the whole app bundle is available and the rest of the files are not encrypted. We’re building a startup to help monitor, analyze and reduce app size and I was able to quickly grab these statistics from the tool we’re working on, here’s a link to a quick demo: https://www.youtube.com/watch?v=3x-hLxxUNm8

I was an iOS engineer at Airbnb when we were battling binary size increases caused by Swift. I rewrote the watch app twice; once to migrate to watchOS 2 and once to convert it all to ObjC (which saved ~9mb). While Swift does have its problems (and had a lot more back when we worked on this), there are many factors to why the Uber app (and Airbnb) is getting so large.

Airbnb is 75% executables, 9.5% assets and 8% localizations. This is pretty different from Uber which is 60.7% executables, 26% localizations and only 3.8% assets. While the Uber executables are large, ~10mb more than Airbnb (note: this is only the Uber rider app, while Airbnb has host+guest in one app), their localizations seem to be driving a lot of the app’s 300+mb install size.

Looking at how the localizations are laid out in the app bundle, there are thousands of *.strings files in separate bundles, seems to be one for each feature. Many of these files have comments to provide context for the strings. An example from the app is: "Various screens show this as a title in a snackbar message when there is no network connectivity available". Just stripping these comments out of the localization files would save about 17.6mb of the install size. Another side effect of splitting localizations into so many files is there are over 23k duplicated strings throughout these bundles.

While the Swift code size is part of the problem with Uber’s app size, it's not the only way to free up space. There's a lot of work that goes into bringing a large scale iOS app’s size down, and not many tools to help. I left my job at Airbnb recently to work on making it easier to visualize, monitor and reduce app size, please email me (noah [at] emergetools.com) if you might be interested!