FileRedirectDylib

A dylib for iOS that hooks file-access functions so games like Bully or GTA San Andreas transparently load modded files from Documents/disk/ instead of the app bundle.

How It Works

On non-jailbroken iOS the .app bundle is read-only. This dylib doesn't try to write into it. Instead it:

1. Hooks C functions: fopen, open, stat, access
2. Swizzles ObjC methods: NSBundle -pathForResource:ofType:, NSFileManager -contentsAtPath:
3. When the game requests a file from its .app bundle, the hook checks if a replacement exists at Documents/disk/<same relative path>
4. If yes → returns the modded file. If no → falls through to the original.

File Structure

FileRedirectDylib/
├── .github/
│   └── workflows/
│       └── build.yml  ← GitHub Actions CI (builds on free macOS runner)
├── tweak.m            ← Main hook/swizzle logic
├── fishhook.h         ← Facebook fishhook header
├── fishhook.c         ← Facebook fishhook implementation
├── Makefile           ← Build script
└── README.md          ← This file

Building — No Mac Required (GitHub Actions)

You do NOT need a Mac. GitHub gives you a free macOS build machine.

Step-by-step:

1. Create a GitHub account if you don't have one: https://github.com
2. Create a new repository (e.g. FileRedirectDylib)
3. Upload all files from this folder to the repo, keeping the folder structure (make sure .github/workflows/build.yml is included)
4. Push / commit — the build runs automatically
5. Go to the Actions tab in your repo
6. Click the latest workflow run → click FileRedirect-dylib under "Artifacts"
7. Download the zip — it contains FileRedirect.dylib ready to inject

You can also trigger a build manually: Actions tab → "Build FileRedirect.dylib" → "Run workflow".

Alternative: Build locally on macOS

If you do have access to a Mac:

cd FileRedirectDylib
make

This produces FileRedirect.dylib targeting iOS arm64 (min iOS 12.0).

Requirements:

• macOS with Xcode or Xcode Command Line Tools
• iOS SDK (included with Xcode)

Injecting into an IPA

Option A: Using insert_dylib

# 1. Unzip the IPA
mkdir payload && cd payload
unzip ../GameName.ipa

# 2. Copy dylib into the .app
cp FileRedirect.dylib Payload/GameName.app/

# 3. Inject the load command
insert_dylib --strip-codesig --inplace \
  @executable_path/FileRedirect.dylib \
  Payload/GameName.app/GameName

# 4. Re-zip as IPA
zip -r ../GameName-modded.ipa Payload/

Option B: Using optool

optool install -c load -p @executable_path/FileRedirect.dylib \
  -t Payload/GameName.app/GameName

Re-signing & Sideloading

After injection, the IPA needs to be re-signed:

• iOS App Signer (macOS GUI) — easiest option
• ldid — ldid -S Payload/GameName.app/GameName
• codesign — codesign -f -s "Apple Development: you@email.com" Payload/GameName.app

Then sideload with:

• AltStore / Sideloadly / TrollStore (if available)

Using Mods

1. Install the modded IPA on your device
2. Open a file manager (e.g. Files app, or via iTunes File Sharing)
3. Navigate to the app's Documents/ folder
4. Create a disk/ subfolder if it doesn't exist (the dylib also auto-creates it)
5. Place your modded files inside disk/, mirroring the .app bundle structure

Example for GTA SA

If the original file is at:

GameName.app/texdb/gta3.txd

Place your modded version at:

Documents/disk/texdb/gta3.txd

The dylib will intercept the read and serve your file instead.

Debugging

The dylib logs all redirected file accesses to the device console. View them with:

# Via Xcode → Window → Devices and Simulators → Open Console
# Or via idevicesyslog:
idevicesyslog | grep "FileRedirect"

Look for lines like:

[FileRedirect] fopen: /var/containers/.../MyApp.app/data/file.dat -> /var/containers/.../Documents/disk/data/file.dat

To disable logging in production, set REDIRECT_LOG_ENABLED to 0 in tweak.m.

Notes

• This works on non-jailbroken iOS via sideloading
• The .app bundle is never modified at runtime — all redirection is in-memory
• If a file is NOT in Documents/disk/, the original bundle file is used (no breakage)
• Compatible with Bully, GTA San Andreas, GTA III, GTA Vice City, Max Payne, and other Rockstar iOS ports