Hi guys! I have gone through an absolute nightmare, trying to solve the issue that I am about to tell you about. As the title says, I am getting the error: Library '/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/17/lib/darwin/libclang_rt.profile_driverkit.a' not found I trimmed off part of that directory as I did not want to reveal that information about my computer. From what I can tell, the file in question is no longer even a part of Xcode. I have searched, it is not on my computer anywhere. I have also downloaded older versions of Xcode to search with it. None of them have it. I have literally tried everything under the Son to solve this issue. I have been stuck on it for two days. I have even resorted to doing something I hate, which is asking for ChatGPT to assist me with solving the issue. No help there. I am at my wits end. So I am coming to you guys, have you seen this error? Any ideas at all? The odds are pretty good whatever you recommend I have probably already tried 200 times over. But I am still open to hearing anything. Have any of you had this error? Any ideas? I am on the latest version of macOS. The project is for a macOS app. M4 Mac mini. Any additional information I can provide, that will be helpful? At this point, I am leaning more towards this being a bug with Xcode than anything.

I'm trying to compile a simple hello world C++ program on my MacBook Pro. I have a M3 Pro (Nov 2023) running Sequoia 15.6. The program is: #include <iostream> int main() { std::cout << "Hello World!"; return 0; } The error I get is: In file included from test.cpp:1: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/iostream:42: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/ios:220: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__locale:15: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__memory/shared_ptr.h:13: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__compare/compare_three_way.h:13: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__compare/three_way_comparable.h:12: In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__compare/common_comparison_category.h:15: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/cstddef:42:5: error: <cstddef> tried including <stddef.h> but didn't find libc++'s <stddef.h> header. This usually means that your header search paths are not configured properly. The header search paths should contain the C++ Standard Library headers before any C Standard Library, and you are probably using compiler flags that make that not be the case. 42 | # error <cstddef> tried including <stddef.h> but didn't find libc++'s <stddef.h> header. \ | ^ However, I can see stddef.h in /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/ and in /usr/local/include

Hi, I have a .NET MAUI app running on .NET 9. When I test locally in debug or release mode it works perfectly fine, but when testing from TestFlight it crashes almost immediately every time. I have sent the crash report to TestFlight and produced the symbolicated.crash file (attached), but I'm not sure it's helpful for understanding how to fix the issue. If anyone can help me understand what the issue might be and any possible fixes it'd be very much appreciated. I'm developing using Visual Studio 2022 paired to my Mac. I have distributed previously without issue, but now can't seem to, even after reverting recent code. net9.0-ios 15.0 symbolicated.crash

Hi, I’m trying to free up space on my computer and have uninstalled Xcode. However, I noticed that many large files remain on the filesystem even after uninstalling it. The largest remaining files (~33 GB) are iOS Simulator images located at: /System/Volumes/Data/Library/Developer/CoreSimulator/Volumes I attempted to delete them using root privileges, but it seems that these system files are mounted as read-only. I’m reaching out to ask for guidance to ensure that these files do not contain anything important for macOS, and that it’s safe to remove them before getting in recovery mode. Thank you very much for your advice!

TL;DR version: AkVox - “Your App in Your User’s Language” Quickly and easily localize your app into as few or as many languages as you want with AkVox. Longer version: AkVox can localize any Xcode project. Simply drag your Exported Localizations folder into AkVox, click translate, then export, and you’re ready to import the translated localizations catalogs back into Xcode. Alas, you cannot import the whole localizations folder as one, you must import each catalog individually, a process that takes around 10 seconds per language. AkVox can also assist you when you’re ready to publish your app on App Store Connect. You can create a list of texts you will enter to promote your app and AkVox will translate them. Again, you can’t apply all your translations to the App Store in ne go, you have to apply each language individually. To make this task less painful, AkVox has a convenient set of buttons to make the copy and paste process as quick and simple as possible. The same arrangement is available when you come to add “mini texts” during setting monetization subscriptions. AkVox employs Google Cloud Translate which means you will need an API Key to be able to run full translations. However, Google offers a generous monthly allowance of 500,000 characters to be translated for free each month. This may well mean that you don’t ever pay for the translation process, just the very low price to use AkVox. The free version of AkVox simulates translating by substituting jumbled versions of Hamlet’s “To be or not to be” speech – this is instead of utilising what would normally be used in this case, the tediously dull Lorem Ipsum text. To see AkVox explained in detail, go to the website: https://akvox.com/

In the availability and pricing section, we have reviewed the plans and we will be upgrading to 50 or 100 million calls/month but before we do, we have a couple questions. Does the API have rate limit or throttling? Do you have additional weather forecast endpoints like hail, radar, or pollen forecast? I see in this thread https://developer.apple.com/forums/thread/795642 that air quality is not available Thanks

Hi everyone! I change my iPhone but I don't find the voice to activate "Developer Mode". I remember that I activated this feature with my old Xs in few minutes. I don't understand.... I must add the 16 Pro and the new Watch 10 for testing in Xcode. How? Thanks!

By default, AppleClang adds /usr/local/include to the application search folders for include files (as opposed to the system include dirs). This causes problems with the expected include order because application search folders always have priority over system includes. Specifically it causes problems with the conan package manager as library includes are added with -isystem This behaviour differs from LLVM mainline clang and GCC, where /usr/local/include is a system include (added with -internal-isystem). Steps to reproduce - run echo 'int main() { return 0; }' | clang -xc -v - the output is as follows Apple clang version 17.0.0 (clang-1700.0.13.5) Target: arm64-apple-darwin24.5.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" ... -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -I/usr/local/include -internal-isystem /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/local/include ...

Hello, I’m trying to test a Xamarin.iOS application using the iOS 26 simulators in Mac Visual Studio, but I’m encountering an issue where the simulators are not appearing or accessible from Visual Studio. Details: macOS version: 15.6 (24G84) Xcode version: 26 Beta 5 Visual Studio version: 17.6.0.80 Xamarin.iOS version: Xamarin.Forms (Version: 4.6.0.1180) using XAML for cross-platform support (iOS/Android) The problem started after updating to iOS 26 SDK. I am unable to select or run the app on any iOS 26 simulator from Visual Studio. Has anyone faced a similar issue? Is there any configuration or workaround to enable iOS 26 simulators for Xamarin projects? Thanks in advance for your help.

I regularly bump into folks confused by this issue, so I thought I’d collect my thoughts on the topic into a single (hopefully) coherent post. If you have questions or comments, put them in a new thread here on the forums. Feel free to use whatever subtopic and tags that apply to your situation, but make sure to add the Debugging tag so that I see your thread go by. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Testing and Debugging Code Running in the Background I regularly see questions like this: My background code works just fine in Xcode but fails when I download the app from the App Store. or this: … or fails when I run my app from the Home screen. or this: How do I step through my background code? These suggest a fundamental misunderstanding of how the debugger interacts with iOS’s background execution model. The goal of this post is to explain that misunderstanding so that you can effectively test and debug background code. Note The focus of this post is iOS. The advice here generally applies to any of iOS’s ‘child’ platforms, so iPadOS, tvOS, and so on. However, there will be some platform specific differences, especially on watchOS. This advice here doesn’t apply to macOS. It’s background execution model is completely different than the one used by iOS. Understand the Fundamentals The key point to note here is that the debugger prevents your app from suspending. This has important consequences for iOS’s background execution model. Normally: iOS suspends your app when it’s in the background. Once your app is suspended, it becomes eligible for termination. The most common reason for this is that the system wants to recover memory, but it can happen for various other reasons. For example, the system might terminate a suspended app in order to update it. Under various circumstances your app can continue running after moving to the background. A great example of this is the continued processed task feature, introduced in iOS 26 beta. Alternatively, your app can be resumed or relaunched in the background to perform some task. For example, the region monitor feature of Core Location can resume or relaunch your app in the background when the user enters or leaves a region. If no app needs to be executing, the system can sleep the CPU. None of this happens in the normal way if the debugger is attached to your app, and it’s vital that you take that into account when debugging code that runs in the background. An Example of the Problem For an example of how this can cause problems, imagine an app that uses an URLSession background session. A background session will resume or relaunch your app in the background when specific events happen. This involves two separate code paths: If your app is suspended, the session resumes it in the background. If your app is terminated, it relaunches it in the background. Neither code path behaves normally if the debugger is attached. In the first case, the app never suspends, so the resume case isn’t properly exercised. Rather, your background session acts like it would if your app were in the foreground. Normally this doesn’t cause too many problems, so this isn’t a huge concern. On the other hand, the second case is much more problematic. The debugger prevents your app from suspending, and hence from terminating, and thus you can’t exercise this code path at all. Seek Framework-Specific Advice The above is just an example, and there are likely other things to keep in mind when debugging background code for a specific framework. Consult the documentation for the framework you’re working with to see if it has specific advice. Note For URLSession background sessions, check out Testing Background Session Code. The rest of this post focuses on the general case, offering advice that applies to all frameworks that support background execution. Run Your App Outside of Xcode When debugging background execution, launch your app from the Home screen. For day-to-day development: Run the app from Xcode in the normal way (Product > Run). Stop it. Run it again from the Home screen. Alternatively, install a build from TestFlight. This accurately replicates the App Store install experience. Write Code with Debugging in Mind It’s obvious that, if you run the app without attaching the debugger, you won’t be able to use the debugger to debug it. Rather: Extract the core logic of your code into libraries, and then write extensive unit tests for those libraries. You’ll be able to debug these unit tests with the debugger. Add log points to help debug your integration with the system. Treat your logging as a feature of your product. Carefully consider where to add log points and at what level to log. Check this logging code into your source code repository and ship it — or at least the bulk of it — as part of your final product. This logging will be super helpful when it comes to debugging problems that only show up in the field. My general advice is that you use the system log for these log points. See Your Friend the System Log for lots of advice on that front. One of the great features of the system log is that disabled log points are very cheap. In most cases it’s fine to leave these in your final product. Attach and Detach In some cases it really is helpful to debug with the debugger. One option here is to attach to your running app, debug a specific thing, and then detach from it. Specifically: To attach to a running app, choose Debug > Attach to Process > YourAppName in Xcode. To detach, choose Debug > Detach. Understand Force Quit iOS allows users to remove an app from the multitasking UI. This is commonly known as force quit, but that’s not a particularly accurate term: The multitasking UI doesn’t show apps that are running, it shows apps that have been run by the user. The UI shows recently run apps regardless of whether they’re in the foreground, running in the background, suspended, or terminated. So, removing an app from the UI may not actually quit anything. Removing an app sets a flag that prevents the app from being launched in the background. That flag gets cleared when the user next launches the app manually. Note In some circumstances iOS will not honour this flag. The exact cases where this happens are not documented and have changed over time. Keep these behaviours in mind as you debug your background execution code. For example, imagine you’re trying to test the URLSession background relaunch code path discussed above. If you force quit your app, you’ll never hit this code path because iOS won’t relaunch your app in the background. Rather, add a debug-only button that causes your app to call exit. IMPORTANT This suggestion is for debugging only. Don’t include a Quit button in your final app! This is specifically proscribed by QA1561. Alternatively, if you’re attached to your app with Xcode, simply choose Product > Stop. This is like calling exit; it has no impact on your app’s ability to run in the background. Test With Various Background App Refresh Settings iOS puts users in control of background execution via the options in Settings > General > Background App Refresh. Test how your app performs with the following settings: Background app refresh turned off overall Background app refresh turned on in general but turned off for your app Background app refresh turned on in general and turned on for your app IMPORTANT While these settings are labelled Background App Refresh, they affect subsystems other than background app refresh. Test all of these cases regardless of what specific background execution feature you’re using. Test Realistic User Scenarios In many cases you won’t be able to fully test background execution code at your desk. Rather, install a TestFlight build of your app and then use the device as a normal user would. For example: To test Core Location background execution properly, actual leave your office and move around as a user might. To test background app refresh, use your app regularly during the day and then put your device on charge at night. Testing like this requires two things: Patience Good logging The system log may be sufficient here, but you might need to investigate other logging solutions that are more appropriate for your product. These testing challenges are why it’s critical that you have unit tests to exercise your core logic. It takes a lot of time to run integration tests like this, so you want to focus on integration issues. Before starting your integration tests, make sure that your unit tests have flushed out any bugs in your core logic. Revision History 2025-08-12 Made various editorial changes. 2025-08-11 First posted.

Hi, experts, I want to find Siri response window by bundle id and use it for checking or printing, here is my example code: XCUIDevice.shared.siriService.activate(voiceRecognitionText: "call mom") let siriApp = XCUIApplication(bundleIdentifier: "***") // Print out text from siriApp, // expecte print: "Sorry, I can't make a phone call with your iphone." Where should I put into ***? I tried "com.apple.SiriViewService", "com.apple.siri.velocity", "com.apple.springboard' but nothing work Any suggestion appreciated, thanks!

Hello, I'm checking to see if anyone else is experiencing an issue downloading the latest beta simulator. When I try to download the iOS 26 beta 5 simulator in Xcode, the download fails instantly. There is no progress, just an immediate error with no message other than the code itself: DVTDownloadableErrorDomain Code: 41. I've already restarted both Xcode and the Mac multiple times. I have also tried downloading on different networks to rule out a firewall issue.

Hi everyone, I'm developing a visionOS application using Unity with an enterprise developer account. I applied for the Main Camera Access entitlement, but at the time of submission, the email address associated with my Apple ID was deactivated, so I couldn’t receive any email communication from Apple. Later, I updated the email address for my Apple ID. Now, in the Apple Developer portal under Identifiers, I can see that my app has been granted Main Camera Access, and I can also add the corresponding capability in Xcode. However, according to Apple’s documentation(https://developer.apple.com/documentation/visionos/building-spatial-experiences-for-business-apps-with-enterprise-apis): “To use entitlements, you need to include both the entitlement file and a corresponding license file in your app. After Apple approves your app for one or more entitlements, you receive a license file, along with additional instructions.” I never received this license file, possibly due to the deactivated email. I don't know where to find it or how to retrieve it now. What exactly is this license file? If it was originally sent to an unreachable email, how can I request it again or get it resent? Where in the Apple Developer portal (or elsewhere) can I access or download this file? Any help or guidance would be greatly appreciated! Thanks in advance.

I've created an installation package and it is failing to install on macOS 15.6. The package is, I believe, properly notarized, since it will install correctly on other macOS versions, including 15.5 The only clue I have is the output from installer: installer[8015] : Opened package is not the same at install time installer[8015] : Unable to use PK session due to incompatible packages. Terminating. installer[8015] : Install failed: The Installer could not install the software because there was no software found to install. The installer consists of a a single "component" package, and the outer "product" package. The component package is present, and I can successfully run installer manually to install it, so I don't think the component package is corrupt. Has anyone else encountered this? Are there any tools available to help me diagnose the issue? The logging is not helpful.

I'm running the latest iOS 26 beta 5 on my iPad and iPhone. Whenever I run these betas, I always get the message below telling me an update is available (whenever I plug in my devices). I'm assuming this is because the update check is detecting that I have something other than the latest production release. Obviously, it makes no sense to ask me to update to a prod build when I'm running the dev beta. Is there a way to turn this message off? Or maybe Apple could handle this situation better? Or maybe it's just a bug and I'm the only one getting this message?

By default, it seems 15.6 is shipped with git version 2.39.5 (Apple Git-154) I was wondering when Apple will ship a Git version above 2.43 to resolve this vulnerability. Git Carriage Return Line Feed (CRLF) Vulnerability (CVE-2025-48384) https://github.com/git/git/security/advisories/GHSA-vwqx-4fm8-6qc9 You can install Homebrew then install newer versions of git using Homebrew; however that installs in a new location so the vulnerability is still present as the native version is behind and updated by Apple during software updates Thanks

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.

Hello All, I used to own an app named LOLIIPOP, and am in the process of transferring it to my new apple account. I am having two problems.... How do I transfer the source code and binary to my new apple account? My developers have an old code, so I need to send them the LAST code they uploaded to the App Store. How do I do that as well??? Please any help!!! Thanks, Mr. LM

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