Apple’s library technology has a long and glorious history, dating all the way back to the origins of Unix. This does, however, mean that it can be a bit confusing to newcomers. This is my attempt to clarify some terminology. If you have any questions or comments about this, start a new thread and tag it with Linker so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" An Apple Library Primer Apple’s tools support two related concepts: Platform — This is the platform itself; macOS, iOS, iOS Simulator, and Mac Catalyst are all platforms. Architecture — This is a specific CPU architecture used by a platform. arm64 and x86_64 are both architectures. A given architecture might be used by multiple platforms. The most obvious example of this arm64, which is used by all of the platforms listed above. Code built for one platform will not work on another platform, even if both platforms use the same architecture. Code is usually packaged in either a Mach-O file or a static library. Mach-O is used for executables (MH_EXECUTE), dynamic libraries (MH_DYLIB), bundles (MH_BUNDLE), and object files (MH_OBJECT). These can have a variety of different extensions; the only constant is that .o is always used for a Mach-O containing an object file. Use otool and nm to examine a Mach-O file. Use vtool to quickly determine the platform for which it was built. Use size to get a summary of its size. Use dyld_info to get more details about a dynamic library. IMPORTANT All the tools mentioned here are documented in man pages. For information on how to access that documentation, see Reading UNIX Manual Pages. There’s also a Mach-O man page, with basic information about the file format. Many of these tools have old and new variants, using the -classic suffix or llvm- prefix, respectively. For example, there’s nm-classic and llvm-nm. If you run the original name for the tool, you’ll get either the old or new variant depending on the version of the currently selected tools. To explicitly request the old or new variants, use xcrun. The term Mach-O image refers to a Mach-O that can be loaded and executed without further processing. That includes executables, dynamic libraries, and bundles, but not object files. A dynamic library has the extension .dylib. You may also see this called a shared library. A framework is a bundle structure with the .framework extension that has both compile-time and run-time roles: At compile time, the framework combines the library’s headers and its stub library (stub libraries are explained below). At run time, the framework combines the library’s code, as a Mach-O dynamic library, and its associated resources. The exact structure of a framework varies by platform. For the details, see Placing Content in a Bundle. macOS supports both frameworks and standalone dynamic libraries. Other Apple platforms support frameworks but not standalone dynamic libraries. Historically these two roles were combined, that is, the framework included the headers, the dynamic library, and its resources. These days Apple ships different frameworks for each role. That is, the macOS SDK includes the compile-time framework and macOS itself includes the run-time one. Most third-party frameworks continue to combine these roles. A static library is an archive of one or more object files. It has the extension .a. Use ar, libtool, and ranlib to inspect and manipulate these archives. The static linker, or just the linker, runs at build time. It combines various inputs into a single output. Typically these inputs are object files, static libraries, dynamic libraries, and various configuration items. The output is most commonly a Mach-O image, although it’s also possible to output an object file. The linker may also output metadata, such as a link map (see Using a Link Map to Track Down a Symbol’s Origin). The linker has seen three major implementations: ld — This dates from the dawn of Mac OS X. ld64 — This was a rewrite started in the 2005 timeframe. Eventually it replaced ld completely. If you type ld, you get ld64. ld_prime — This was introduced with Xcode 15. This isn’t a separate tool. Rather, ld now supports the -ld_classic and -ld_new options to select a specific implementation. Note During the Xcode 15 beta cycle these options were -ld64 and -ld_prime. I continue to use those names because the definition of new changes over time (some of us still think of ld64 as the new linker ;–). The dynamic linker loads Mach-O images at runtime. Its path is /usr/lib/dyld, so it’s often referred to as dyld, dyld, or DYLD. Personally I pronounced that dee-lid, but some folks say di-lid and others say dee-why-el-dee. IMPORTANT Third-party executables must use the standard dynamic linker. Other Unix-y platforms support the notion of a statically linked executable, one that makes system calls directly. This is not supported on Apple platforms. Apple platforms provide binary compatibility via system dynamic libraries and frameworks, not at the system call level. Note Apple platforms have vestigial support for custom dynamic linkers (your executable tells the system which dynamic linker to use via the LC_LOAD_DYLINKER load command). This facility originated on macOS’s ancestor platform and has never been a supported option on any Apple platform. The dynamic linker has seen 4 major revisions. See WWDC 2017 Session 413 (referenced below) for a discussion of versions 1 through 3. Version 4 is basically a merging of versions 2 and 3. The dyld man page is chock-full of useful info, including a discussion of how it finds images at runtime. Every dynamic library has an install name, which is how the dynamic linker identifies the library. Historically that was the path where you installed the library. That’s still true for most system libraries, but nowadays a third-party library should use an rpath-relative install name. For more about this, see Dynamic Library Identification. Mach-O images are position independent, that is, they can be loaded at any location within the process’s address space. Historically, Mach-O supported the concept of position-dependent images, ones that could only be loaded at a specific address. While it may still be possible to create such an image, it’s no longer a good life choice. Mach-O images have a default load address, also known as the base address. For modern position-independent images this is 0 for library images and 4 GiB for executables (leaving the bottom 32 bits of the process’s address space unmapped). When the dynamic linker loads an image, it chooses an address for the image and then rebases the image to that address. If you take that address and subtract the image’s load address, you get a value known as the slide. Xcode 15 introduced the concept of a mergeable library. This a dynamic library with extra metadata that allows the linker to embed it into the output Mach-O image, much like a static library. Mergeable libraries have many benefits. For all the backstory, see WWDC 2023 Session 10268 Meet mergeable libraries. For instructions on how to set this up, see Configuring your project to use mergeable libraries. If you put a mergeable library into a framework structure you get a mergeable framework. Xcode 15 also introduced the concept of a static framework. This is a framework structure where the framework’s dynamic library is replaced by a static library. Note It’s not clear to me whether this offers any benefit over creating a mergeable framework. Earlier versions of Xcode did not have proper static framework support. That didn’t stop folks trying to use them, which caused all sorts of weird build problems. A universal binary is a file that contains multiple architectures for the same platform. Universal binaries always use the universal binary format. Use the file command to learn what architectures are within a universal binary. Use the lipo command to manipulate universal binaries. A universal binary’s architectures are either all in Mach-O format or all in the static library archive format. The latter is called a universal static library. A universal binary has the same extension as its non-universal equivalent. That means a .a file might be a static library or a universal static library. Most tools work on a single architecture within a universal binary. They default to the architecture of the current machine. To override this, pass the architecture in using a command-line option, typically -arch or --arch. An XCFramework is a single document package that includes libraries for any combination of platforms and architectures. It has the extension .xcframework. An XCFramework holds either a framework, a dynamic library, or a static library. All the elements must be the same type. Use xcodebuild to create an XCFramework. For specific instructions, see Xcode Help > Distribute binary frameworks > Create an XCFramework. Historically there was no need to code sign libraries in SDKs. If you shipped an SDK to another developer, they were responsible for re-signing all the code as part of their distribution process. Xcode 15 changes this. You should sign your SDK so that a developer using it can verify this dependency. For more details, see WWDC 2023 Session 10061 Verify app dependencies with digital signatures and Verifying the origin of your XCFrameworks. A stub library is a compact description of the contents of a dynamic library. It has the extension .tbd, which stands for text-based description (TBD). Apple’s SDKs include stub libraries to minimise their size; for the backstory, read this post. Use the tapi tool to create and manipulate stub libraries. In this context TAPI stands for a text-based API, an alternative name for TBD. Oh, and on the subject of tapi, I’d be remiss if I didn’t mention tapi-analyze! Stub libraries currently use YAML format, a fact that’s relevant when you try to interpret linker errors. If you’re curious about the format, read the tapi-tbdv4 man page. There’s also a JSON variant documented in the tapi-tbdv5 man page. Note Back in the day stub libraries used to be Mach-O files with all the code removed (MH_DYLIB_STUB). This format has long been deprecated in favour of TBD. Historically, the system maintained a dynamic linker shared cache, built at runtime from its working set of dynamic libraries. In macOS 11 and later this cache is included in the OS itself. Libraries in the cache are no longer present in their original locations on disk: % ls -lh /usr/lib/libSystem.B.dylib ls: /usr/lib/libSystem.B.dylib: No such file or directory Apple APIs, most notably dlopen, understand this and do the right thing if you supply the path of a library that moved into the cache. That’s true for some, but not all, command-line tools, for example: % dyld_info -exports /usr/lib/libSystem.B.dylib /usr/lib/libSystem.B.dylib [arm64e]: -exports: offset symbol … 0x5B827FE8 _mach_init_routine % nm /usr/lib/libSystem.B.dylib …/nm: error: /usr/lib/libSystem.B.dylib: No such file or directory When the linker creates a Mach-O image, it adds a bunch of helpful information to that image, including: The target platform The deployment target, that is, the minimum supported version of that platform Information about the tools used to build the image, most notably, the SDK version A build UUID For more information about the build UUID, see TN3178 Checking for and resolving build UUID problems. To dump the other information, run vtool. In some cases the OS uses the SDK version of the main executable to determine whether to enable new behaviour or retain old behaviour for compatibility purposes. You might see this referred to as compiled against SDK X. I typically refer to this as a linked-on-or-later check. Apple tools support the concept of autolinking. When your code uses a symbol from a module, the compiler inserts a reference (using the LC_LINKER_OPTION load command) to that module into the resulting object file (.o). When you link with that object file, the linker adds the referenced module to the list of modules that it searches when resolving symbols. Autolinking is obviously helpful but it can also cause problems, especially with cross-platform code. For information on how to enable and disable it, see the Build settings reference. Mach-O uses a two-level namespace. When a Mach-O image imports a symbol, it references the symbol name and the library where it expects to find that symbol. This improves both performance and reliability but it precludes certain techniques that might work on other platforms. For example, you can’t define a function called printf and expect it to ‘see’ calls from other dynamic libraries because those libraries import the version of printf from libSystem. To help folks who rely on techniques like this, macOS supports a flat namespace compatibility mode. This has numerous sharp edges — for an example, see the posts on this thread — and it’s best to avoid it where you can. If you’re enabling the flat namespace as part of a developer tool, search the ’net for dyld interpose to learn about an alternative technique. WARNING Dynamic linker interposing is not documented as API. While it’s a useful technique for developer tools, do not use it in products you ship to end users. Apple platforms use DWARF. When you compile a file, the compiler puts the debug info into the resulting object file. When you link a set of object files into a executable, dynamic library, or bundle for distribution, the linker does not include this debug info. Rather, debug info is stored in a separate debug symbols document package. This has the extension .dSYM and is created using dsymutil. Use symbols to learn about the symbols in a file. Use dwarfdump to get detailed information about DWARF debug info. Use atos to map an address to its corresponding symbol name. Different languages use different name mangling schemes: C, and all later languages, add a leading underscore (_) to distinguish their symbols from assembly language symbols. C++ uses a complex name mangling scheme. Use the c++filt tool to undo this mangling. Likewise, for Swift. Use swift demangle to undo this mangling. For a bunch more info about symbols in Mach-O, see Understanding Mach-O Symbols. This includes a discussion of weak references and weak definition. If your code is referencing a symbol unexpectedly, see Determining Why a Symbol is Referenced. To remove symbols from a Mach-O file, run strip. To hide symbols, run nmedit. It’s common for linkers to divide an object file into sections. You might find data in the data section and code in the text section (text is an old Unix term for code). Mach-O uses segments and sections. For example, there is a text segment (__TEXT) and within that various sections for code (__TEXT > __text), constant C strings (__TEXT > __cstring), and so on. Over the years there have been some really good talks about linking and libraries at WWDC, including: WWDC 2023 Session 10268 Meet mergeable libraries WWDC 2022 Session 110362 Link fast: Improve build and launch times WWDC 2022 Session 110370 Debug Swift debugging with LLDB WWDC 2021 Session 10211 Symbolication: Beyond the basics WWDC 2019 Session 416 Binary Frameworks in Swift — Despite the name, this covers XCFrameworks in depth. WWDC 2018 Session 415 Behind the Scenes of the Xcode Build Process WWDC 2017 Session 413 App Startup Time: Past, Present, and Future WWDC 2016 Session 406 Optimizing App Startup Time Note The older talks are no longer available from Apple, but you may be able to find transcripts out there on the ’net. Historically Apple published a document, Mac OS X ABI Mach-O File Format Reference, or some variant thereof, that acted as the definitive reference to the Mach-O file format. This document is no longer available from Apple. If you’re doing serious work with Mach-O, I recommend that you find an old copy. It’s definitely out of date, but there’s no better place to get a high-level introduction to the concepts. The Mach-O Wikipedia page has a link to an archived version of the document. For the most up-to-date information about Mach-O, see the declarations and doc comments in <mach-o/loader.h>. Revision History 2025-08-04 Added a link to Determining Why a Symbol is Referenced. 2025-06-29 Added information about autolinking. 2025-05-21 Added a note about the legacy Mach-O stub library format (MH_DYLIB_STUB). 2025-04-30 Added a specific reference to the man pages for the TBD format. 2025-03-01 Added a link to Understanding Mach-O Symbols. Added a link to TN3178 Checking for and resolving build UUID problems. Added a summary of the information available via vtool. Discussed linked-on-or-later checks. Explained how Mach-O uses segments and sections. Explained the old (-classic) and new (llvm-) tool variants. Referenced the Mach-O man page. Added basic info about the strip and nmedit tools. 2025-02-17 Expanded the discussion of dynamic library identification. 2024-10-07 Added some basic information about the dynamic linker shared cache. 2024-07-26 Clarified the description of the expected load address for Mach-O images. 2024-07-23 Added a discussion of position-independent images and the image slide. 2024-05-08 Added links to the demangling tools. 2024-04-30 Clarified the requirement to use the standard dynamic linker. 2024-03-02 Updated the discussion of static frameworks to account for Xcode 15 changes. Removed the link to WWDC 2018 Session 415 because it no longer works )-: 2024-03-01 Added the WWDC 2023 session to the list of sessions to make it easier to find. Added a reference to Using a Link Map to Track Down a Symbol’s Origin. Made other minor editorial changes. 2023-09-20 Added a link to Dynamic Library Identification. Updated the names for the static linker implementations (-ld_prime is no more!). Removed the beta epithet from Xcode 15. 2023-06-13 Defined the term Mach-O image. Added sections for both the static and dynamic linkers. Described the two big new features in Xcode 15: mergeable libraries and dependency verification. 2023-06-01 Add a reference to tapi-analyze. 2023-05-29 Added a discussion of the two-level namespace. 2023-04-27 Added a mention of the size tool. 2023-01-23 Explained the compile-time and run-time roles of a framework. Made other minor editorial changes. 2022-11-17 Added an explanation of TAPI. 2022-10-12 Added links to Mach-O documentation. 2022-09-29 Added info about .dSYM files. Added a few more links to WWDC sessions. 2022-09-21 First posted.

Recently a bunch of folks have asked about why a specific symbol is being referenced by their app. This is my attempt to address that question. If you have questions or comments, please start a new thread. Tag it with Linker so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Determining Why a Symbol is Referenced In some situations you might want to know why a symbol is referenced by your app. For example: You might be working with a security auditing tool that flags uses of malloc. You might be creating a privacy manifest and want to track down where your app is calling stat. This post is my attempt at explaining a general process for tracking down the origin of these symbol references. This process works from ‘below’. That is, it works ‘up’ from you app’s binary rather than ‘down’ from your app’s source code. That’s important because: It might be hard to track down all of your source code, especially if you’re using one or more package management systems. If your app has a binary dependency on a static library, dynamic library, or framework, you might not have access to that library’s source code. IMPORTANT This post assumes the terminology from An Apple Library Primer. Read that before continuing here. The general outline of this process is: Find all Mach-O images. Find the Mach-O image that references the symbol. Find the object files (.o) used to make that Mach-O. Find the object file that references the symbol. Find the code within that object file. Those last few steps require some gnarly low-level Mach-O knowledge. If you’re looking for an easier path, try using the approach described in the A higher-level alternative section as a replacement for steps 3 through 5. This post assumes that you’re using Xcode. If you’re using third-party tools that are based on Apple tools, and specifically Apple’s linker, you should be able to adapt this process to your tooling. If you’re using a third-party tool that has its own linker, you’ll need to ask for help via your tool’s support channel. Find all Mach-O images On Apple platforms an app consists of a number of Mach-O images. Every app has a main executable. The app may also embed dynamic libraries or frameworks. The app may also embed app extensions or system extensions, each of which have their own executable. And a Mac app might have embedded bundles, helper tools, XPC services, agents, daemons, and so on. To find all the Mach-O images in your app, combine the find and file tools. For example: % find "Apple Configurator.app" -print0 | xargs -0 file | grep Mach-O Apple Configurator.app/Contents/MacOS/Apple Configurator: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64] … Apple Configurator.app/Contents/MacOS/cfgutil: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64] … Apple Configurator.app/Contents/Extensions/ConfiguratorIntents.appex/Contents/MacOS/ConfiguratorIntents: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64] … Apple Configurator.app/Contents/Frameworks/ConfigurationUtilityKit.framework/Versions/A/ConfigurationUtilityKit: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit dynamically linked shared library x86_64] [arm64] … This shows that Apple Configurator has a main executable (Apple Configurator), a helper tool (cfgutil), an app extension (ConfiguratorIntents), a framework (ConfigurationUtilityKit), and many more. This output is quite unwieldy. For nicer output, create and use a shell script like this: % cat FindMachO.sh #! /bin/sh # Passing `-0` to `find` causes it to emit a NUL delimited after the # file name and the `:`. Sadly, macOS `cut` doesn’t support a nul # delimiter so we use `tr` to convert that to a DLE (0x01) and `cut` on # that. # # Weirdly, `find` only inserts the NUL on the primary line, not the # per-architecture Mach-O lines. We use that to our advantage, filtering # out the per-architecture noise by only passing through lines # containing a DLE. find "$@" -type f -print0 \ | xargs -0 file -0 \ | grep -a Mach-O \ | tr '\0' '\1' \ | grep -a $(printf '\1') \ | cut -d $(printf '\1') -f 1 Find the Mach-O image that references the symbol Once you have a list of Mach-O images, use nm to find the one that references the symbol. The rest of this post investigate a test app, WaffleVarnishORama, that’s written in Swift but uses waffle management functionality from the libWaffleCore.a static library. The goal is to find the code that calls calloc. This app has a single Mach-O image: % FindMachO.sh "WaffleVarnishORama.app" WaffleVarnishORama.app/WaffleVarnishORama Use nm to confirm that it references calloc: % nm "WaffleVarnishORama.app/WaffleVarnishORama" | grep "calloc" U _calloc The _calloc symbol has a leading underscore because it’s a C symbol. This convention dates from the dawn of Unix, where the underscore distinguish C symbols from assembly language symbols. The U prefix indicates that the symbol is undefined, that is, the Mach-O images is importing the symbol. If the symbol name is prefixed by a hex number and some other character, like T or t, that means that the library includes an implementation of calloc. That’s weird, but certainly possible. OTOH, if you see this then you know this Mach-O image isn’t importing calloc. IMPORTANT If this Mach-O isn’t something that you build — that is, you get this Mach-O image as a binary from another developer — you won’t be able to follow the rest of this process. Instead, ask for help via that library’s support channel. Find the object files used to make that Mach-O image The next step is to track down which .o file includes the reference to calloc. Do this by generating a link map. A link map is an old school linker feature that records the location, size, and origin of every symbol added to the linker’s output. To generate a link map, enable the Write Link Map File build setting. By default this puts the link map into a text (.txt) file within the derived data directory. To find the exact path, look at the Link step in the build log. If you want to customise this, use the Path to Link Map File build setting. A link map has three parts: A simple header A list of object files used to build the Mach-O image A list of sections and their symbols In our case the link map looks like this: # Path: …/WaffleVarnishORama.app/WaffleVarnishORama # Arch: arm64 # Object files: [ 0] linker synthesized [ 1] objc-file [ 2] …/AppDelegate.o [ 3] …/MainViewController.o [ 4] …/libWaffleCore.a[2](WaffleCore.o) [ 5] …/Foundation.framework/Foundation.tbd … # Sections: # Address Size Segment Section 0x100008000 0x00001AB8 __TEXT __text … The list of object files contains: An object file for each of our app’s source files — That’s AppDelegate.o and MainViewController.o in this example. A list of static libraries — Here that’s just libWaffleCore.a. A list of dynamic libraries — These might be stub libraries (.tbd), dynamic libraries (.dylib), or frameworks (.framework). Focus on the object files and static libraries. The list of dynamic libraries is irrelevant because each of those is its own Mach-O image. Find the object file that references the symbol Once you have list of object files and static libraries, use nm to each one for the calloc symbol: % nm "…/AppDelegate.o" | grep calloc % nm "…/MainViewController.o" | grep calloc % nm "…/libWaffleCore.a" | grep calloc U _calloc This indicates that only libWaffleCore.a references the calloc symbol, so let’s focus on that. Note As in the Mach-O case, the U prefix indicates that the symbol is undefined, that is, the object file is importing the symbol. Find the code within that object file To find the code within the object file that references the symbol, use the objdump tool. That tool takes an object file as input, but in this example we have a static library. That’s an archive containing one or more object files. So, the first step is to unpack that archive: % mkdir "libWaffleCore-objects" % cd "libWaffleCore-objects" % ar -x "…/libWaffleCore.a" % ls -lh total 24 -rw-r--r-- 1 quinn staff 4.1K 8 May 11:24 WaffleCore.o -rw-r--r-- 1 quinn staff 56B 8 May 11:24 __.SYMDEF SORTED There’s only a single object file in that library, which makes things easy. If there were a multiple, run the following process over each one independently. To find the code that references a symbol, run objdump with the -S and -r options: % xcrun objdump -S -r "WaffleCore.o" … ; extern WaffleRef newWaffle(void) { 0: d10083ff sub sp, sp, #32 4: a9017bfd stp x29, x30, [sp, #16] 8: 910043fd add x29, sp, #16 c: d2800020 mov x0, #1 10: d2800081 mov x1, #4 ; Waffle * result = calloc(1, sizeof(Waffle)); 14: 94000000 bl 0x14 <ltmp0+0x14> 0000000000000014: ARM64_RELOC_BRANCH26 _calloc … Note the ARM64_RELOC_BRANCH26 line. This tells you that the instruction before that — the bl at offset 0x14 — references the _calloc symbol. IMPORTANT The ARM64_RELOC_BRANCH26 relocation is specific to the bl instruction in 64-bit Arm code. You’ll see other relocations for other instructions. And the Intel architecture has a whole different set of relocations. So, when searching this output don’t look for ARM64_RELOC_BRANCH26 specifically, but rather any relocation that references _calloc. In this case we’ve built the object file from source code, so WaffleCore.o contains debug symbols. That allows objdump include information about the source code context. From that, we can easily see that calloc is referenced by our newWaffle function. To see what happens when you don’t have debug symbols, create an new object file with them stripped out: % cp "WaffleCore.o" "WaffleCore-stripped.o" % strip -x -S "WaffleCore-stripped.o" Then repeat the objdump command: % xcrun objdump -S -r "WaffleCore-stripped.o" … 0000000000000000 <_newWaffle>: 0: d10083ff sub sp, sp, #32 4: a9017bfd stp x29, x30, [sp, #16] 8: 910043fd add x29, sp, #16 c: d2800020 mov x0, #1 10: d2800081 mov x1, #4 14: 94000000 bl 0x14 <_newWaffle+0x14> 0000000000000014: ARM64_RELOC_BRANCH26 _calloc … While this isn’t as nice as the previous output, you can still see that newWaffle is calling calloc. A higher-level alternative Grovelling through Mach-O object files is quite tricky. Fortunately there’s an easier approach: Use the -why_live option to ask the linker why it included a reference to the symbol. To continue the above example, I set the Other Linker Flags build setting to -Xlinker / -why_live / -Xlinker / _calloc and this is what I saw in the build transcript: _calloc from /usr/lib/system/libsystem_malloc.dylib _newWaffle from …/libWaffleCore.a[2](WaffleCore.o) _$s18WaffleVarnishORama18MainViewControllerC05tableE0_14didSelectRowAtySo07UITableE0C_10Foundation9IndexPathVtFTf4dnn_n from …/MainViewController.o _$s18WaffleVarnishORama18MainViewControllerC05tableE0_14didSelectRowAtySo07UITableE0C_10Foundation9IndexPathVtF from …/MainViewController.o Demangling reveals a call chain like this: calloc newWaffle WaffleVarnishORama.MainViewController.tableView(_:didSelectRowAt:) WaffleVarnishORama.MainViewController.tableView(_:didSelectRowAt:) and that should be enough to kick start your investigation. IMPORTANT The -why_live option only works if you dead strip your Mach-O image. This is the default for the Release build configuration, so use that for this test. Revision History 2025-07-18 Added the A higher-level alternative section. 2024-05-08 First posted.

Dear Apple Developer Support, We are experiencing a critical issue after upgrading our development environment from Xcode 15 to Xcode 16 (beta). Our iOS application integrates Flutter via CocoaPods (install_all_flutter_pods and flutter_post_install) and uses plugins like webview_flutter. After the upgrade, our project started failing at the linking stage with the following errors: Undefined symbol: _XPluginsGetDataFuncOrAbort Undefined symbol: _XPluginsGetFunctionPtrFromID Undefined symbol: Plugins::SocketThreadLocalScope::SocketThreadLocalScope(int) Undefined symbol: Plugins::SocketThreadLocalScope::~SocketThreadLocalScope() Linker command failed with exit code 1 These symbols seem to originate from Flutter’s new native C++ plugin architecture (possibly via webview_flutter_wkwebview), and were previously resolving fine with Xcode 15. We have ensured the following: Added -lc++ and -ObjC to OTHER_LDFLAGS Cleaned and rebuilt Flutter module via flutter build ios --release Re-installed CocoaPods with pod install Verified Flutter.xcframework and plugin xcframeworks are present Despite this, the linker fails to resolve the mentioned symbols under Xcode 16. This suggests a stricter linker behavior or a compatibility issue with the new C++ plugin system Flutter uses. Can you confirm: If Xcode 16 introduces stricter C++/Objective-C++ linker constraints? Is there an official workaround or updated documentation for dealing with Plugins::SocketThreadLocalScope and related symbol resolution? Should these symbols be declared explicitly or provided in .xcframework format from plugin developers? We would appreciate guidance or clarification on how to proceed with Flutter plugin compatibility under Xcode 16. Thank you.

I'm trying to run a simple C++ script, but for some reason I keep getting an error. Where /usr/lib/libc++.1.dylib cannot be found. Specifically, dyld[2012]: dyld cache '(null)' not loaded: syscall to map cache into shared region failed dyld[2012]: Library not loaded: /usr/lib/libc++.1.dylib Reason: tried: '/usr/lib/libc++.1.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/usr/lib/libc++.1.dylib' (no such file), '/usr/lib/libc++.1.dylib' (no such file, no dyld cache) I tried reinstalling Xcode with no success. Can I get some help?

Hi ! I'm currently stuck with an issue on Xcode, I'll try explain to the best I can :-) I have a workspace (that I need to keep that way, I can't split projects) that contains multiple projects. I have 2 frameworks : Core and Draw. Draw depends on Core. So far so good. I needed to create a test application that can be modular and link my framewok, but also other drawing frameworks. To that extend, I created a CardLIbrary framewok, and a CardAdapter framewok, and I linked them into the test application. Test App └── DrawCardAdapter │ └── CardAdapter │ └── CardLibrary │ └── Core │ └── TCA (SPM) │ └── Draw │ └── Core Here, all dependencies are local ones if not stated otherwise (for the SPM). CardLibrary is a framework that generates only UI (linked to Core for logging purposes, nothing fancy). I also added TCA which is a SPM dependency, it may generate some issues after. CardAdapter is an abstraction for CardLibrary. Basically, it acts as an interface between CardLibrary and Test Application. DrawCardAdapter is the actual implementation of CardAdapter using local Draw framework. Why so complex ? Because I need to be able to do this: Test App └── ExternalDrawCardAdapter │ └── CardAdapter │ └── CardLibrary │ └── Core │ └── TCA (SPM) │ └── ExternalDrawFramework With this architecture, I can create a new ExternalDrawCardAdapter that implents the CardAdapter logic. This new framework does not relies on my Draw framework, and yet, I can still generate a test application that visually looks and feel like all others, but use a completely different drawing engine underneath. To do that, the Test App code only uses inputs and outputs from CardAdapter (the protocol), not concrete implementations like DrawCardAdapter or ExternalDrawCardAdapter. But to be able to make it work, I have 2 test ap targets : a DrawTestApp and a ExternalDrawTestApp. All code files are shared, except a SdkLauncher that is target specific and acutally loads the proper implementation. So the SdkLauncher for DrawTestApp is linked to the DrawCardAdapter (embed and sign) and loads DrawCardAdapter framework, whereas the ExternalDrawTestApp is linked to the ExternalDrawCardAdapter (embed and sign) and loads ExternalDrawCardAdapter framework. Now it looks like this (I only show local stuff othewise it would be too complicated :D) So far so good, this works well. Now, for the part that fails. My Draw and Core frameworks are frameworks that I release for my customers (Cocoapod), and I wanted to be able to test my productions frameworks with the test app (it's that actual purpose of the test app : being able to test development and released SDKs) To do so, I duplicated every target and removed local dependency for a cocoapod dependency. All targets were named -pod, but the actual module and product name are still the same (I tried differently, it did not work either, I'll explain it later). Test App └── DrawCardAdapter │ └── CardAdapter │ └── CardLibrary │ └── Core │ └── TCA (SPM) │ └── Draw │ └── Core │ Test App Pod └── DrawCardAdapter-pod │ └── CardAdapter-pod │ └── CardLibrary-pod │ └── Core-pod │ └── TCA (SPM) │ └── Draw-pod │ └── Core-pod Once again, it's only targets, every project would look like CardAdapter └── CardAdapter └── CardAdapter-pod It continues to use local targets, except for the DrawCardAdapter-pod that actually loads Draw and Core from a Podfile instead of using the lkocal frameworks. But now for the part that fails : even though TestApp-pod does not link any local frameworks, I get a warning Multiple targets match implicit dependency for product reference 'Draw.framework'. Consider adding an explicit dependency on the intended target to resolve this ambiguity. And actually, Xcode ends up packaging the wrong framework. I can check it but showing in the app the Draw framework version, and it's always the local one, not the one specified in the podfile. For the record, I get this message for all 3 frameworks of course. I tried sooooo many things, that did not work of course: renaming the -pod frameworks so that the names are different (I had to rename all imports too). It works for all local frameworks (Lilbrary and Adapter basically), but not for Draw and Core (since I don't have -podversions of thoses framewoks of course). Creating a new local workspace that only handles -pod versions. Does not work since as we work as a team, I have to keep the shared schemes, and all workspaces see all targets and schemes. I also tried with a separate derived data folder, but I end up with some compilation issues. It seems that mixing local, cocoapod and spm dependencies inside the same workspace is not well handled) using explicit Target Dependenciesfrom the build phase. I end up with some compilation issues creating local podspecs for Library and Adapter. It fails because TCA is linked with SPM and apparently not copied when using podspecs. To the few ones that stayed so far, thanks for your patience :D I hope that @eskimo will drop by as you always were my savior in the end :D :D

​Environment​： Xcode Version: 16.0 (latest stable release) iOS Version: 18.3.1 Devices: physical devices Configuration: Main Thread Checker enabled (Edit Scheme &amp;gt; Run &amp;gt; Diagnostics) ​Issue Description​ When the ​Main Thread Checker​ is enabled, methods defined in a UIViewController category (e.g., supportedInterfaceOrientations) fail to execute, whereas the subclass implementation of the same method works as expected. This conflicts with the normal behavior where ​both implementations should be called. ​Steps to Reproduce​ 1、Declare a category method in UIViewController+Extend.m: // UIViewController+Extend.m @implementation UIViewController (Extend) - (UIInterfaceOrientationMask)supportedInterfaceOrientations { NSLog(@"category supportedInterfaceOrientations hit"); return UIInterfaceOrientationMaskAll; } @end 2、Override the same method in a subclass ，call super methed(ViewController.m): // ViewController.m @implementation ViewController - (UIInterfaceOrientationMask)supportedInterfaceOrientations { NSLog(@"subclass called supportedInterfaceOrientations called"); return [super supportedInterfaceOrientations]; // Expected to call the category implementation } @end 3、​Expected Behavior​ (Main Thread Checker ​disabled): subclass called supportedInterfaceOrientations called category supportedInterfaceOrientations hit 4、Actual Behavior​ (Main Thread Checker ​enabled): subclass called supportedInterfaceOrientations called // category supportedInterfaceOrientations hit ​Requested Resolution​ Please investigate: 1、Why Main Thread Checker disrupts category method invocation. 2、Whether this is a broader issue affecting other UIKit categories.

Hi, I encountered an issue in my code where I directly used #import <CoreHaptics/CoreHaptics.h> without adding it to the "Link Binary With Libraries" section under Build Phases. My deployment target is iOS 12, and the code was running fine before; however, after upgrading Xcode, the app crashes immediately on an iOS 12 device with the following error message: DYLD, Library not loaded: /System/Library/Frameworks/CoreHaptics.framework/CoreHaptics | xx | Reason: image not found. Did Xcode modify the default auto-linking configuration? When did this behavior change in which version of Xcode? Do I need to specify CoreHaptics.framework as Optional in "Link Binary With Libraries"? Thanks for reply soon!

I have an app (currently in development stage) which needs to use ffmpeg, so I tried searching how to embed ffmpeg in apple apps and found this article https://doc.qt.io/qt-6/qtmultimedia-building-ffmpeg-ios.html It is working correctly for iOS but not for macOS ( I have made changes macOS specific using chatgpt and traditional web searching) Drive link for the file and instructions which I'm following: https://drive.google.com/drive/folders/11wqlvb8SU2thMSfII4_Xm3Kc2fPSCZed?usp=share_link Please can someone from apple or in general help me to figure out what I'm doing wrong?

I'm encountering a crash on app launch. The crash is observed in iOS version 17.6 but not in iOS version 18.5. The only new notable thing I added to this app version was migrate to store kit 2. Below is the error message from Xcode: Referenced from: &lt;DCC68597-D1F6-32AA-8635-FB975BD853FE&gt; /private/var/containers/Bundle/Application/6FB3DDE4-6AD5-4778-AD8A-896F99E744E8/callbreak.app/callbreak Expected in: &lt;A0C8B407-0ABF-3C28-A54C-FE8B1D3FA7AC&gt; /usr/lib/swift/libswift_Concurrency.dylib Symbol not found: _$sScIsE4next9isolation7ElementQzSgScA_pSgYi_tYa7FailureQzYKFTu Referenced from: &lt;DCC68597-D1F6-32AA-8635-FB975BD853FE&gt; /private/var/containers/Bundle/Application/6FB3DDE4-6AD5-4778-AD8A-896F99E744E8/callbreak.app/callbreak Expected in: &lt;A0C8B407-0ABF-3C28-A54C-FE8B1D3FA7AC&gt; /usr/lib/swift/libswift_Concurrency.dylib dyld config: DYLD_LIBRARY_PATH=/usr/lib/system/introspection DYLD_INSERT_LIBRARIES=/usr/lib/libLogRedirect.dylib:/usr/lib/libBacktraceRecording.dylib:/usr/lib/libMainThreadChecker.dylib:/usr/lib/libRPAC.dylib:/System/Library/PrivateFrameworks/GPUToolsCapture.framework/GPUToolsCapture:/usr/lib/libViewDebuggerSupport.dylib``` and Stack Trace: ```* thread #1, stop reason = signal SIGABRT * frame #0: 0x00000001c73716f8 dyld`__abort_with_payload + 8 frame #1: 0x00000001c737ce34 dyld`abort_with_payload_wrapper_internal + 104 frame #2: 0x00000001c737ce68 dyld`abort_with_payload + 16 frame #3: 0x00000001c7309dd4 dyld`dyld4::halt(char const*, dyld4::StructuredError const*) + 304 frame #4: 0x00000001c73176a8 dyld`dyld4::prepare(...) + 4088 frame #5: 0x00000001c733bef4 dyld`start + 1748``` Note: My app is a Godot App and uses objc static libraries. I am using swift with bridging headers for interoperability. This issue wasn't observed until my last version in which the migration to storekit2 was the only notable change.

I'm having a problem with Xcode 26 where a symbol bug is causing my app to crash at launch if they are running iOS 17.X This has to do with a HealthKit API that was introduced in iOS 18.1 HKQuantityType(.appleSleepingBreathingDisturbances), I use availability clauses to ensure I only support it in that version. This all worked fine with Xcode 16.4 but breaks in Xcode 26. This means ALL my users running iOS 17 will get at launch crashes if this isn't resolved in the Xcode GM seed. I'll post the code here in case I'm doing anything wrong. This, the HealthKit capability, the "HealthKit Privacy - Health Share Usage Description" and "Privacy - Health Update Usage Description", and device/simulator on iOS 17.X are all you need to reproduce the issue. I've made a feedback too as I'm 95% sure it's a bug: FB19727966 import SwiftUI import HealthKit struct ContentView: View { var body: some View { VStack { Image(systemName: "globe") .imageScale(.large) .foregroundStyle(.tint) Text("Hello, world!") } .padding() .task { print(await requestPermission()) } } } #Preview { ContentView() } func requestPermission() async -> Bool { if #available(iOS 18.0, *) { let healthTypes = [HKQuantityType(.appleSleepingBreathingDisturbances)] var readTypes = healthTypes.map({$0}) let write: Set<HKSampleType> = [] let res: ()? = try? await HKHealthStore().requestAuthorization(toShare: write, read: Set(readTypes)) guard res != nil else { print("requestPermission returned nil") return false } return true } else { return false} }

Is anyone have this problem on xcode 26 ? Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibility50 Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibility51 Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibility56 Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibilityConcurrency Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibilityDynamicReplacements

I admit I am doing something unusual, and I would not be surprised if it didn't work. I am surprised, however, because after performing the equivalent operations on four bundles, all of the bundles work fine on macOS 15.6.1, but only two of them work on macOS 26.1 (beta 2). I don't know what causes the different outcomes. What I am trying to do is get Java to pass the macOS 26 AppKit UI SDK linkage checking without having to rebuild the JDK using Xcode 26. Rebuilding works for the latest SDK, but it is very inconvenient and may not work for older JDKs. It usually takes a while before the JDK build team successfully transitions to a new Xcode release. My approach is to use vtool to update the sdk version in the LC_BUILD_VERSION load command of $JAVA_HOME/bin/java, which is the launching executable for the JDK. I performed this operation on four JDKs: 25, 21, 17, and 11. (I ran vtool on macOS 15.) It was completely successful on JDK 25 and 21. The JDK launches correctly on macOS 15 and macOS 26. On macOS 26, AppKit uses the new UI, which is the desired outcome. The JDK runs despite that fact that I signed the modified $JAVA_HOME/bin/java with my developer ID, which is inconsistent with the JDK bundle signature. (Redoing the bundle signing is part of the JDK build process; if that were necessary, I would stick with rebuilding the JDK.) The operation was not successful on JDK 17 and 11. I noticed two problems, which are not obviously related. When vtool created the new version of the java program, it lost the tool definition. $ vtool -show-build-version java java: Load command 10 cmd LC_BUILD_VERSION cmdsize 32 platform MACOS minos 11.0 sdk 11.1 ntools 1 tool LD version 609.8 $ vtool -set-build-version 1 10.0 26.0 -output a.out java /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/vtool warning: code signature will be invalid for a.out $ vtool -show-build-version a.out a.out: Load command 22 cmd LC_BUILD_VERSION cmdsize 24 platform MACOS minos 10.0 sdk 26.0 ntools 0 Adding back the tool definition didn't seem to matter. When I try to run the revised executable (in the context of the JDK bundle), it works on macOS 15, but on macOS 26, it is rejected as damaged. If I run the revised executable outside the JDK bundle, it runs (but fails because it can't find the rest of the JDK, which is expected). In all cases, GateKeeper rejects the revised executable because it has not been notarized, but that doesn't seem to stop the program from executing.

LLVM Linker Crash on ARM64 with bfloat16 Symbols (Xcode 17.0.0) We're encountering a critical linker crash in Xcode 17.0.0 (clang-1700.4.4.1) on macOS 15.1.0 (Darwin 25.1.0) with Apple Silicon M3 Max when linking a pybind11 C++ extension against the MLX framework (v0.30.1). The linker consistently crashes with LLVM ERROR: No way to correctly truncate anything but float to bfloat during the linking phase, even though our code uses only integer types (int64, uint32) for BPE tokenization and never directly references bfloat16 types. Error Details: [100%] Linking CXX shared module _metal_trainer.cpython-312-darwin.so LLVM ERROR: No way to correctly truncate anything but float to bfloat clang++: error: unable to execute command: Abort trap: 6 clang++: error: linker command failed due to signal (use -v to see invocation) Reproduction: Install MLX framework: pip install mlx (any version with bfloat16 support) Create a minimal pybind11 extension that links against MLX: Compiler: AppleClang 17.0.0.17000404 Target: arm64-apple-darwin25.1.0 Flags: -std=c++17 -O2 -march=native Link against: libmlx.dylib (contains bfloat16 symbols) Run: cmake .. && make Linker crashes during final linking phase Root Cause: The LLVM ARM64 backend in Xcode 17.0.0 has a code generation bug when processing bfloat16 truncation operations during link-time. The crash occurs when the linker processes bfloat16 symbols from libmlx.dylib, regardless of whether the application code uses them. The error originates from LLVM's type legalization pass attempting to truncate bfloat16 values, but the ARM64 backend lacks a valid code path for this operation. Workarounds Attempted (all failed): Disabling LTO: INTERPROCEDURAL_OPTIMIZATION FALSE Linker flags: -Wl,-no_compact_unwind, -fno-lto Runtime symbol resolution: -undefined dynamic_lookup Compiler optimizations: Changed from -O3 to -O2 Impact: This blocks any C++ extension development that links against libraries containing bfloat16 symbols on Xcode 17.0.0. The issue does not occur on Xcode 16.x. Linker Crash Dump Location: /var/folders/gn/7_g6wy1j66b8z3lkywyrbsx00000gn/T/linker-crash-* Expected Behavior: Linker should successfully link the extension, or at minimum, gracefully handle bfloat16 symbols without crashing. Temporary Solution: Downgrade to Xcode 16.x or use Python-only implementations until this is fixed in a future Xcode release.

I want to create a dynamic library for my iOS project, which would be loaded at runtime. In Xcode, there are templates available for creating a static/dynamic lib for MacOS. But under the iOS tab, there is only a "static library" template. So, I used the "static library" template and in its build settings I changed the Mach-O type to "dynamic library". Now after building it, I use the file command on the generated file and it tells me it is a dynamic lib. But the generated file still has .a extension, which is usually for static libs. I'm aware we can tell Xcode in build settings to change the .a extension to something else, say .dylib but this seems like a hacky way to create a dynamic library. What is the correct way? I am aware that standalone dylibs are not supported on iOS, and we need to wrap them in a framework. For my use case, the framework will literally be a wrapper, it won't have any source files of its own. It should only contain the dynamic lib generated from some independent codebase. I am not sure how to place the dylib in the framework.

In our app, we implement a document picker using FilePickerManager+available.m, selecting different APIs based on the iOS version: if (@available(iOS 14.0, *)) { NSMutableArray<UTType *> *contentTypes = [NSMutableArray array]; for (NSString *uti in documentTypes) { UTType *type = [UTType typeWithIdentifier:uti]; if (type) { [contentTypes addObject:type]; NSLog(@"iOS 14+ Adding type: %@", uti); } else { NSLog(@"Warning: Unable to create UTI: %@", uti); } } UIDocumentPickerViewController *documentPicker = [[UIDocumentPickerViewController alloc] initForOpeningContentTypes:contentTypes]; documentPicker.delegate = self; documentPicker.allowsMultipleSelection = NO; [self.presentingViewController presentViewController:documentPicker animated:YES completion:nil]; } However, we've observed inconsistent symbol reference types to UTType in the final linked binaries: One build results in a strong reference to UTType. Another demo project (with seemingly identical code and build settings) results in a weak reference. Both object files (.o) show undefined references to UTType symbols (e.g., UTTypeCreatePreferredIdentifierForTag), yet the final linked binaries differ in how these symbols are resolved. Impact of the Issue This inconsistency causes problems on iOS 14.0+ devices: Strong reference version: Fails to launch on devices where the UniformTypeIdentifiers framework is not present (e.g., certain older iOS 14.x devices), due to link-time failure. Weak reference version: Launches successfully but crashes at runtime when attempting to call UTType methods, because the implementation cannot be found. Our Analysis Using nm -u, both versions show an undefined symbol: U _UTTypeCreatePreferredIdentifierForTag However, in the final binaries: One shows: T _UTTypeCreatePreferredIdentifierForTag (strong) The other shows: W _UTTypeCreatePreferredIdentifierForTag (weak) Both projects link against the framework identically in their build logs: -framework UniformTypeIdentifiers (no -weak_framework flag is used in either case). Questions Why do identical source code and linker flags result in different symbol reference strengths (T vs W) for the same framework? Are there specific compiler or linker behaviors (e.g., deployment target, SDK version, module imports, or bitcode settings) that influence whether symbols from UniformTypeIdentifiers are treated as strong or weak? What is the recommended best practice to ensure consistent symbol referencing when using newer APIs like UTType, especially when supporting older OS versions? We aim to understand this behavior to guarantee stable operation across all supported iOS versions—avoiding both launch failures and runtime crashes caused by inconsistent symbol linking. Any insights or guidance from the community or Apple engineers would be greatly appreciated! Let me know if you'd like a shorter version or want to include additional build environment details (Xcode version, deployment target, etc.)!

In our app, we implement a document picker using FilePickerManager+available.m, selecting different APIs based on the iOS version: if (@available(iOS 14.0, *)) { NSMutableArray<UTType *> *contentTypes = [NSMutableArray array]; for (NSString *uti in documentTypes) { UTType *type = [UTType typeWithIdentifier:uti]; if (type) { [contentTypes addObject:type]; NSLog(@"iOS 14+ Adding type: %@", uti); } else { NSLog(@"Warning: Unable to create UTI: %@", uti); } } UIDocumentPickerViewController *documentPicker = [[UIDocumentPickerViewController alloc] initForOpeningContentTypes:contentTypes]; documentPicker.delegate = self; documentPicker.allowsMultipleSelection = NO; [self.presentingViewController presentViewController:documentPicker animated:YES completion:nil]; } However, we've observed inconsistent symbol reference types to UTType in the final linked binaries: One build results in a strong reference to UTType. Another demo project (with seemingly identical code and build settings) results in a weak reference. Both object files (.o) show undefined references to UTType symbols (e.g., UTTypeCreatePreferredIdentifierForTag), yet the final linked binaries differ in how these symbols are resolved. Impact of the Issue This inconsistency causes problems on iOS 14.0+ devices: Strong reference version: Fails to launch on devices where the UniformTypeIdentifiers framework is not present (e.g., certain older iOS 14.x devices), due to link-time failure. Weak reference version: Launches successfully but crashes at runtime when attempting to call UTType methods, because the implementation cannot be found. Our Analysis Using nm -u, both versions show an undefined symbol: U _UTTypeCreatePreferredIdentifierForTag However, in the final binaries: One shows: T _UTTypeCreatePreferredIdentifierForTag (strong) The other shows: W _UTTypeCreatePreferredIdentifierForTag (weak) Both projects link against the framework identically in their build logs: -framework UniformTypeIdentifiers (no -weak_framework flag is used in either case). Questions Why do identical source code and linker flags result in different symbol reference strengths (T vs W) for the same framework? Are there specific compiler or linker behaviors (e.g., deployment target, SDK version, module imports, or bitcode settings) that influence whether symbols from UniformTypeIdentifiers are treated as strong or weak? What is the recommended best practice to ensure consistent symbol referencing when using newer APIs like UTType, especially when supporting older OS versions? We aim to understand this behavior to guarantee stable operation across all supported iOS versions—avoiding both launch failures and runtime crashes caused by inconsistent symbol linking. Any insights or guidance from the community or Apple engineers would be greatly appreciated! Let me know if you'd like a shorter version or want to include additional build environment details (Xcode version, deployment target, etc.)!

good.load_commands.txt I bad.load_commands.txt have two dylibs built with different parameters on different machines. Both have the same dependency(@rpath/libc++.dylib). When @rpath/libc++.dylib is missing, one of them can still be laoded via dlopen with RTLD_NOW, and I want to understand why. Additional infomation: Both dylibs are the same architecture(arm64) They had identical LC_RPATH settings. But I've removed them via install_name_tool just to simplify the problem. Through otool -l to view load commands, I can't find any differnent between them except they had different libSystem.B.dylib version. And then,I through setting DYLD_PRINT_SEARCHING=1 and load them. I found differenes in their dependency search processes, but' I'm unsure what causes this discrepancy. these are outputs: ./a.out libchrome_zlib.dylib.good dyld[37001]: find path "/usr/lib/libc++.1.dylib" dyld[37001]: possible path(original path on disk): "/usr/lib/libc++.1.dylib" dyld[37001]: possible path(cryptex prefix): "/System/Volumes/Preboot/Cryptexes/OS/usr/lib/libc++.1.dylib" dyld[37001]: possible path(original path): "/usr/lib/libc++.1.dylib" dyld[37001]: found: dylib-from-cache: (0x000A) "/usr/lib/libc++.1.dylib" dyld[37001]: find path "/usr/lib/libSystem.B.dylib" dyld[37001]: possible path(original path on disk): "/usr/lib/libSystem.B.dylib" dyld[37001]: possible path(cryptex prefix): "/System/Volumes/Preboot/Cryptexes/OS/usr/lib/libSystem.B.dylib" dyld[37001]: possible path(original path): "/usr/lib/libSystem.B.dylib" dyld[37001]: found: dylib-from-cache: (0x00AB) "/usr/lib/libSystem.B.dylib" dyld[37001]: find path "libchrome_zlib.dylib.good" dyld[37001]: possible path(original path on disk): "libchrome_zlib.dylib.good" dyld[37001]: found: dylib-from-disk: "libchrome_zlib.dylib.good" dyld[37001]: find path "@rpath/libc++.dylib" dyld[37001]: possible path(default fallback): "/usr/local/lib/libc++.dylib" dyld[37001]: possible path(default fallback): "/usr/lib/libc++.dylib" dyld[37001]: found: dylib-from-cache: (0x000A) "/usr/lib/libc++.dylib" ./a.out libchrome_zlib.dylib.bad dyld[41256]: find path "/usr/lib/libc++.1.dylib" dyld[41256]: possible path(original path on disk): "/usr/lib/libc++.1.dylib" dyld[41256]: possible path(cryptex prefix): "/System/Volumes/Preboot/Cryptexes/OS/usr/lib/libc++.1.dylib" dyld[41256]: possible path(original path): "/usr/lib/libc++.1.dylib" dyld[41256]: found: dylib-from-cache: (0x000A) "/usr/lib/libc++.1.dylib" dyld[41256]: find path "/usr/lib/libSystem.B.dylib" dyld[41256]: possible path(original path on disk): "/usr/lib/libSystem.B.dylib" dyld[41256]: possible path(cryptex prefix): "/System/Volumes/Preboot/Cryptexes/OS/usr/lib/libSystem.B.dylib" dyld[41256]: possible path(original path): "/usr/lib/libSystem.B.dylib" dyld[41256]: found: dylib-from-cache: (0x00AB) "/usr/lib/libSystem.B.dylib" dyld[41256]: find path "libchrome_zlib.dylib.bad" dyld[41256]: possible path(original path on disk): "libchrome_zlib.dylib.bad" dyld[41256]: found: dylib-from-disk: "libchrome_zlib.dylib.bad" dyld[41256]: find path "@rpath/libc++.dylib" dyld[41256]: not found: "@rpath/libc++.dylib" dlopen failed: dlopen(libchrome_zlib.dylib.bad, 0x0002): Library not loaded: @rpath/libc++.dylib Referenced from: <42E93041-7B58-365B-9967-04AE754AA9F0> /Users/jiangzh/dlopen/libchrome_zlib.dylib.bad Reason: no LC_RPATH's found

I have reference some related post for this issue: https://developer.apple.com/documentation/xcode-release-notes/xcode-16-release-notes#Foundation https://developer.apple.com/forums/thread/762711 Unfortunately, I'm facing the similar issues even though using Xcode Version 16.2 (16C5032a). we have the following build environment: Xcode version: Xcode 16.2 (16C5032a) macOS Version: macOS 14.7.4 (23H420) Everything builds and install fine. But when attempting to plug on Device on macOS 14.7.4 it crashes immediately with what appears to be a missing Foundation symbol. Crashed Thread: 0 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: Namespace DYLD, Code 4 Symbol missing Symbol not found: __ZThn48_N21IOUserNetworkEthernet25registerEthernetInterfaceE10ether_addrPP24IOUserNetworkPacketQueuejP29IOUserNetworkPacketBufferPoolS5_ Referenced from: &lt;ECE57ABF-0633-3C3B-8427-FB25CC706343&gt; /Library/SystemExtensions/*/com.asix.dext.pciedevice Expected in: &lt;CDEB3490-B1E0-3D60-80CE-59C0682A4B03&gt; /System/DriverKit/System/Library/Frameworks/NetworkingDriverKit.framework/NetworkingDriverKit (terminated at launch; ignore backtrace) Thread 0 Crashed: 0 dyld 0x1041da4c8 __abort_with_payload + 8 1 dyld 0x1041e50cc abort_with_payload_wrapper_internal + 104 2 dyld 0x1041e5100 abort_with_payload + 16 3 dyld 0x1041767f0 dyld4::halt(char const*, dyld4::StructuredError const*) + 304 4 dyld 0x1041732ec dyld4::prepare(dyld4::APIs&amp;, dyld3::MachOAnalyzer const*) + 3888 5 dyld 0x104171ef4 start + 1868 Thread 0 crashed with ARM Thread State (64-bit): x0: 0x0000000000000006 x1: 0x0000000000000004 x2: 0x000000016bdd2810 x3: 0x0000000000000172 x4: 0x000000016bdd2410 x5: 0x0000000000000000 x6: 0x000000016bdd1400 x7: 0x000000016bdd1460 x8: 0x0000000000000020 x9: 0x000000016bdd237c x10: 0x000000000000000a x11: 0x0000000000000000 x12: 0x0000000000000038 x13: 0x0000000000000000 x14: 0x0000000188e77f9d x15: 0x0000000000008000 x16: 0x0000000000000209 x17: 0x000000010416f37c x18: 0x0000000000000000 x19: 0x0000000000000000 x20: 0x000000016bdd2410 x21: 0x0000000000000172 x22: 0x000000016bdd2810 x23: 0x0000000000000004 x24: 0x0000000000000006 x25: 0x00000000000000a8 x26: 0x000000016bdd32d8 x27: 0x000000010405e090 x28: 0x0000000000000001 fp: 0x000000016bdd23e0 lr: 0x00000001041e50cc sp: 0x000000016bdd23a0 pc: 0x00000001041da4c8 cpsr: 0x80001000 far: 0x0000000000000000 esr: 0x56000080 Address size fault Binary Images: 0x10416c000 - 0x1041f7fff dyld (*) &lt;4fe051cf-29dc-3f02-890b-33144fa09253&gt; /usr/lib/dyld 0x10402c000 - 0x10403ffff com.asix.dext.pciedevice (0.1.6) &lt;ece57abf-0633-3c3b-8427-fb25cc706343&gt; /Library/SystemExtensions/*/com.asix.dext.pciedevice 0x0 - 0xffffffffffffffff ??? (*) &lt;00000000-0000-0000-0000-000000000000&gt; ??? External Modification Summary: Calls made by other processes targeting this process: task_for_pid: 0 thread_create: 0 thread_set_state: 0 Calls made by this process: task_for_pid: 0 thread_create: 0 thread_set_state: 0 Calls made by all processes on this machine: task_for_pid: 0 thread_create: 0 thread_set_state: 0 VM Region Summary: ReadOnly portion of Libraries: Total=8612K resident=0K(0%) swapped_out_or_unallocated=8612K(100%) Writable regions: Total=12.2M written=0K(0%) resident=0K(0%) swapped_out=0K(0%) unallocated=12.2M(100%) Is it expected that this should work? Is this a known issue? Is there any workaround for it? Should I file feedback or a DTS?

Hi, I encounter problems after updating macOS to Sequoia 15.5 with plugins loaded with dlopen and dlsym. $ file /Applications/com.gsequencer.GSequencer.app/Contents/Plugins/ladspa/cmt.dylib /Applications/com.gsequencer.GSequencer.app/Contents/Plugins/ladspa/cmt.dylib: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit bundle x86_64] [arm64:Mach-O 64-bit bundle arm64] /Applications/com.gsequencer.GSequencer.app/Contents/Plugins/ladspa/cmt.dylib (for architecture x86_64): Mach-O 64-bit bundle x86_64 /Applications/com.gsequencer.GSequencer.app/Contents/Plugins/ladspa/cmt.dylib (for architecture arm64): Mach-O 64-bit bundle arm64 I am currently investigating what goes wrong. My application runs in a sandboxed environment.

Hello I have a qt, CMAKE app, non-xcode one till xcode start supporting cmake. I have 3 apps, 2 basic ones and 1 very complex ones. My complex one build/links/notarises/validates/deploys beautifly. I have tear in my eye when I see it build. The other 2 apps explode and torment me for past 5 days. The build proves is 99% the same, the only thing that a little changes are info.plist and app name+ some minor changes. Its absolutely bananas and I can't fix it, I'm running out of ideas so if any1 could sugged anything, I'll buy &amp; ship you a beer. Anyway, errors: Log: Using otool: Log: inspecting "/Users/dariusz/Qt/6.9.1/macos/lib/QtCore.framework/Versions/A/QtCore" Log: Could not parse otool output line: "/Users/dariusz/Qt/6.9.1/macos/lib/QtCore.framework/Versions/A/QtCore (architecture arm64):" Log: Adding framework: Log: Framework name "QtCore.framework" Framework directory "/Users/dariusz/Qt/6.9.1/macos/lib/" Framework path "/Users/dariusz/Qt/6.9.1/macos/lib/QtCore.framework" Binary directory "Versions/A" Binary name "QtCore" Binary path "/Versions/A/QtCore" Version "A" Install name "@rpath/QtCore.framework/Versions/A/QtCore" Deployed install name "@rpath/QtCore.framework/Versions/A/QtCore" Source file Path "/Users/dariusz/Qt/6.9.1/macos/lib/QtCore.framework/Versions/A/QtCore" Framework Destination Directory (relative to bundle) "Contents/Frameworks/QtCore.framework" Binary Destination Directory (relative to bundle) "Contents/Frameworks/QtCore.framework/Versions/A" Log: copied: "/Users/dariusz/Qt/6.9.1/macos/lib/QtWebSockets.framework/Versions/A/QtWebSockets" Log: to "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/Versions/A/QtWebSockets" Log: copy: "/Users/dariusz/Qt/6.9.1/macos/lib/QtWebSockets.framework/Resources" "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/Versions/A/Resources" Log: copied: "/Users/dariusz/Qt/6.9.1/macos/lib/QtWebSockets.framework/Resources/Info.plist" Log: to "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/Versions/A/Resources/Info.plist" Log: copied: "/Users/dariusz/Qt/6.9.1/macos/lib/QtWebSockets.framework/Resources/PrivacyInfo.xcprivacy" Log: to "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/Versions/A/Resources/PrivacyInfo.xcprivacy" Log: symlink "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/QtWebSockets" Log: points to "Versions/Current/QtWebSockets" Log: symlink "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/Resources" Log: points to "Versions/Current/Resources" Log: symlink "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/Frameworks/QtWebSockets.framework/Versions/Current" Log: points to "A" Log: Using install_name_tool: Log: in "/AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/MacOS/Agameri_Toolbox" Log: change reference "@rpath/QtWebSockets.framework/Versions/A/QtWebSockets" Log: to "@rpath/QtWebSockets.framework/Versions/A/QtWebSockets" ERROR: "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/install_name_tool: fatal error: file not in an order that can be processed (link edit information does not fill the __LINKEDIT segment): /AppBuild/Agameri_Toolbox/Agameri_Toolbox.app/Contents/MacOS/Agameri_Toolbox\n" ERROR: "" Even tho I get that error, it will "Notarize" and "greenlight by gatekeeper. So my automatic build app if he sees error with the __LINKEDIT it will stop deployment. But even tho he "stops" release of app to public I can still go check binary and when I try to run that I get: Library not loaded: @rpath/QtConcurrent.framework/Versions/A/QtConcurrent Referenced from: &lt;69A296DB-8C7D-3BC9-A8AE-947B8D6ED224&gt; /Volumes/VOLUME/*/Agameri_Toolbox.app/Contents/MacOS/Agameri_Toolbox Reason: tried: '/Users/dariusz/Qt/6.9.1/macos/lib/QtConcurrent.framework/Versions/A/QtConcurrent' (code signature in &lt;192D5FAC-FE8C-31AB-86A7-6C2CE5D3E864&gt; '/Users/dariusz/Qt/6.9.1/macos/lib/QtConcurrent.framework/Versions/A/QtConcurrent' not valid for use in process: mapping process and mapped file (non-platform) have different Team IDs), '/System/Volumes/Preboot/Cryptexes/OS/Users/dariusz/Qt/6.9.1/macos/lib/QtConcurrent.framework/Versions/A/QtConcurrent' (no such file), '/Volumes/DEV_MAC/02_CODE/Dev/Icarus.nosync/Icarus_Singleton/codeSingleton/libOutput/Release/QtConcurrent.framework/Versions/A/QtConcurrent' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/Volumes/DEV_MAC/02_CODE/Dev/Icarus.nosync/Icarus_Singleton/codeSingleton/libOu (terminated at launch; ignore backtrace) And here is my build script, its QT based application, I'm using macdeployqt + my own custom signing as the one from macdeployqt breaks on the complex app. (I will post it in next post as apparently there is 7k limit O.O) I've tried to replace the @rpath/ to @executable_path but that has made a million new issues and I'm just lost.