This is a continuation of https://developer.apple.com/forums/thread/795348 I rambled too much and did not understand the underlaying problem. The problem is that I have a C function in a iOS library. I want to call this C function from a dylib that this library loads on runtime. When running directly from Xcode (either in debug or release mode) this works correctly. However, when the app is uploaded to testflight or distributed for debugging then the function is stripped and a null function pointer exception crashes the app. In the last post it was really hard to explain and I was pressed on time but I've created a minimal reproducible example: https://github.com/ospfranco/dylib_crash The instructions to run and reproduce the crash are on the README.

This is a lengthy one. I have basically compiled a Rust binary into a dylib and packaged into a .xcframework that contains per arch .frameworks. This loads correctly when run from Xcode into a real iOS device. However, when deployed to TestFlight the app crashes. Here is what is a bit different, the dylib is not fully self-contained. It tries to reach in an use C functions I have exposed in my library code. Calling functions that are just within the dylib and just return works fine, but the moment it tries to call one of the exposed functions it crashes. A full in-depth step by step of how I packaged the binaries can be found in my website: https://ospfranco.com/complete-guide-to-dylibs-in-ios-and-android When I look at the TestFlight crash report there are no symbols but the termination cause via WatchDog is: Termination Reason: CODESIGNING 2 Invalid Page I have declared my functions as such: OBJC_EXTERN void ios_prepare_request(const char *url) #define EXPORT __attribute__((visibility("default"), used, retain)) extern "C" { EXPORT void ios_prepare_request(const char *url) { NSString *urlString = [NSString stringWithUTF8String:url]; request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:urlString]]; } } // Function used to prevent optimization void force_symbol_registration() { // Force these symbols to be included in the binary by referencing them volatile void *ptrs[] = {(void *)ios_prepare_request,}; // Prevent compiler from optimizing away the array (void)ptrs; } And I load my framework as: opacity::force_symbol_registration(); // NSBundle *dylib_bundle = // [NSBundle bundleWithIdentifier:@"com.opacitylabs.sdk"]; // NSString *dylib_path = [dylib_bundle pathForResource:@"sdk" ofType:@""]; // // Load the dynamic library // void *handle = dlopen([dylib_path UTF8String], RTLD_NOW | RTLD_GLOBAL); // if (!handle) { // NSString *errorMessage = [NSString stringWithUTF8String:dlerror()]; // *error = // [NSError errorWithDomain:@"OpacitySDKDylibError" // code:1002 // userInfo:@{NSLocalizedDescriptionKey : // errorMessage}]; // return -1; // or appropriate error code // } // Make sure the main executable's symbols are available dlopen(NULL, RTLD_NOW | RTLD_GLOBAL); NSBundle *frameworkBundle = [NSBundle bundleWithIdentifier:@"com.opacitylabs.sdk"]; if (![frameworkBundle isLoaded]) { BOOL success = [frameworkBundle load]; if (!success) { NSString *errorMessage = @"Failed to load framework"; *error = [NSError errorWithDomain:@"OpacitySDKDylibError" code:1002 userInfo:@{NSLocalizedDescriptionKey : errorMessage}]; return -1; } } As you can see, I have also tried dlopen both work when run from Xcode but crash when deployed on testflight. I have tried re-signing the xcframework/frameworks on a pre build step but it doesn't work As stated, I can call the functions inside the dylib, but once they try to call my exposed code it crashes Is this achievable at all or just a limitation of the iOS sandbox?