Alexey Alter-Pesotskiy

2 minute read

Profiling app size on iOS

Intro

Today I’d like to show you how to do a proper size analysis of an App or an SDK on iOS.

I’ll try to be as short as possible, so fasten the seat belts 🤠

Building the app

Let’s create a new empty app and integrate some third-party SDK via SPM. For example StreamChatSwiftUI.

1. Open Xcode
2. Create New Project... -> iOS App -> Product name: `Size`; Interface: `SwiftUI` -> Next -> Create
3. File -> Add Package Dependencies -> `stream-chat-swiftui` -> Add Package -> Add to Target: `Size` -> Add Package
5. Make sure the `DEBUG_INFORMATION_FORMAT` build setting is set to `DWARF with dSYM File` for more detailed analysis
4. Select a development team in the Signing & Capabilities editor
5. Product -> Archive -> `Size.xcarchive`

Profiling the size

This is where we get to a crossroads, because there are a bunch of ways to get the size of a binary.

We will look at some of them, from the simplest to those that offer the most comprehensive analysis.

Disk Usage CLI

  1. Measure your app

     app_path="Size.xcarchive/Products/Applications/Size.app"
 size_in_mb=$(echo "scale=2; $(du -sk "${app_path}" | cut -f1) / 1024" | bc)
 echo "$size_in_mb MB"
    • Where:
     * `du` is an abbreviation for "Disk Usage"
 * `bc` is an abbreviation for "Basic Calculator" or "Bash Calculator"
 * `1024` is the number of KB in MB
 * `scale=2` is an argument to round the result to required number of decimal places
 * `-sk` is an argument to get the size of a file/folder in KB
 * `cut -f1` is an argument to get rid of the file path in the output
    • Result:
     13.23 MB

  2. Measure your binary

     app_binary_path="Size.xcarchive/Products/Applications/Size.app/Size"
 size_in_mb=$(echo "scale=2; $(du -sk "${app_binary_path}" | cut -f1) / 1024" | bc)
 echo "$size_in_mb MB"
    • Result:
     12.08 MB

Bloaty

  1. Install bloaty, a size profiler for binaries, crafted by Google

     brew install bloaty

  2. Profile you binary

     app_binary_path="Size.xcarchive/Products/Applications/Size.app/Size"
 dsym_binary_path="Size.xcarchive/dSYMs/Size.app.dSYM/Contents/Resources/DWARF/Size"
 bloaty ${app_binary_path} --debug-file=${dsym_binary_path} -d compileunits -n 0

  • Where:

      * `-d compileunits` is an argument to get app size split per file
  * `-n 0` is an argument to specify the maximum fetch depth

  • Result:

         FILE SIZE       VM SIZE
  --------------  --------------
    8.1%  1004Ki   7.9%  1004Ki    [__TEXT,__text]
    6.8%   837Ki   6.7%   848Ki    [__LINKEDIT]
    2.4%   293Ki   2.3%   293Ki    /Library/Developer/Xcode/DerivedData/Size-chfnnfxxtxfvxabrjimspcolpjyk/SourcePackages/checkouts/stream-chat-swift/Sources/StreamChat/WebSocketClient/Events/MessageEvents.swift
    2.4%   292Ki   2.3%   292Ki    [__DATA_CONST,__const]
    2.4%   291Ki   2.3%   291Ki    /Library/Developer/Xcode/DerivedData/Size-chfnnfxxtxfvxabrjimspcolpjyk/SourcePackages/checkouts/stream-chat-swiftui/Sources/StreamChatSwiftUI/ChatChannelList/SearchResultsView.swift
    0.0%       0   2.1%   261Ki    [__DATA,__bss]
    1.9%   234Ki   1.9%   234Ki    [__TEXT,__const]
    1.9%   231Ki   1.8%   231Ki    [__DATA,__data]
    1.6%   198Ki   1.6%   198Ki    [__TEXT,__swift5_typeref]
    1.5%   184Ki   1.5%   184Ki    /Library/Developer/Xcode/DerivedData/Size-chfnnfxxtxfvxabrjimspcolpjyk/SourcePackages/checkouts/stream-chat-swiftui/Sources/StreamChatSwiftUI/ChatChannelList/ChatChannelNavigatableListItem.swift
    1.4%   170Ki   1.4%   170Ki    /Library/Developer/Xcode/DerivedData/Size-chfnnfxxtxfvxabrjimspcolpjyk/SourcePackages/checkouts/stream-chat-swift/Sources/StreamChat/ChatClient.swift
    ...
    ...
    ...
  100.0%  12.1Mi 100.0%  12.3Mi    TOTAL

Emerge Tools

And finally, let’s see the magic Emerge Tools is capable of 🪄

1. Zip your app's xcarchive: `zip -r Size.zip Size.xcarchive`
2. Sign up for a free account at emergetools.com
3. Verify your email
4. Open emergetools.com/dashboard
5. Uploads -> Upload a local build -> Drag your `Size.zip`
6. Click on the `View build analysis` link
7. Point to any module to find out its size or search for any filename, class name, etc...
Preview

Postscript

If you want to get an idea of how a third-party SDK affects the size of your app, just do the same without importing an SDK and compare the results.

Updated: