I have just finished porting a decent amount of c-sources to the iOS platform and packaged them as a universal static framework. I, then, added the framework (not the project) to a sample iOS app in order to test linkage and proper function. That's when I ran into a humbling problem.
In my attempt to solve the problem described here, I also came across some symbols that are composed through the heavy use of macros (i HATE those). Some of those macros use function attributes that are really extensions of gcc rather than of standard C.
Of course I can always add -std=gnu89, but even then, I am not sure it will resolve the original problem of undefined symbols in the static library.
Not only that, I am now worried that my port to iOS of those sources may not be an accurate port and may result in the type of bugs/issues that maybe related to compiler's codeine and/or optimization policies.
If you can share some of your experience/advice in how best to go about that port, I would really appreciate it.
Thanks!
From manual testing with clang 8.0, it seems that both __attribute__((constructor)) and __attribute__((__constructor__)) work for your purpose.
Related
This is a variant of the old "dyld: Library not loaded: #rpath/libswiftCore.dylib" problem. I'm pretty sure I know what the issue is, but I don't have any ideas on how to fix it.
I'll reference the project I'm working on, so I don't clutter the question with huge blocks of code.
The project generates a dylib that can be thrown into another project, and abstract a huge block of coding for developers (a communication layer of a client/server system).
I want the framework to be as simple as possible to to use; even if that means making it a big fat pig. I just want people to be able to toss it into their project (Swift or ObjC), and not have to worry about playing around with different variants for things like simulators and devices.
I use a variant of the old Wenderlich script to lipo the executables for x86 and ARM together.
Note the commented-out section. There be draggones.
Works great. In Swift.
Objective-C, not so great. That's because of the various Swift frameworks that need to be carried into the Objective-C program.
I switched on the embed frameworks setting, and the target dutifully gives me all my frameworks.
The problem is that each architecture has frameworks for ONLY that architecture. They aren't "fat" frameworks, so my hand-built "fat" framework really is kinda skinny, because it will only work on certain architectures.
My question is whether or not there's a way to ensure that the Swift frameworks I embed can be made "fat," or if I just have to give up, and package different variants of the framework for Objective-C programmers.
Any ideas?
I'm giving up on this sucker.
You cain't git thar f'm here.
This library will be Swift-only.
I recently tried to use Armadillo on iOS to do some matrix computing. The App worked on my development iPhone, but Apple gave me the error message when trying to publish it in the Appstore. It seems that Armadillo calls some BLAS functions which are internal. I searched the web with the message, but had not found anything useful. I also found calling BLAS functions with "cblas_" prefix, e.g. cblas_dgemv, directly from my code would not cause the error. However, that made the use of armadillo meaningless.
I wonder if anyone has encountered the same problem, and what the solution is. I’m suspecting it’s something related to some macro in config.hpp. Thank you very much for your kindly help.
Error message:
Non-public API usage:
• The app references non-public symbols in ***: _sgemm_, _sgemv_, _ssyrk_
The Accelerate BLAS implementation supports a bunch of redundant symbols to facilitate divergent function naming schemes of various fortran compilers. Strictly speaking these are intended to be used (by your fortran compiler) so you probably have some arguing ground that they are not private interfaces. If the AppStore is still giving you trouble, file a bug against Apple and ask them to fix the bookkeeping on the interfaces so they can be used.
It would be simpler to just start using the cblas_ interfaces in the headers though.
If I create an Xcode project with the iOS Single View Application template and choose Swift for the language, will the compiler exclude from the release build (binary) functions that never get called?
I'm wondering because I want to include a third-party library that has a lot of superfluous classes & functions, and I want to keep my app small & fast.
While I agree with comments, it is unlikely to impact performance in any significant way even if it was included...
Xcode 6 uses Apple LLVM Compiler Version 6.1, depending on how closely related it is to LLVM Developer Group's version the optimization feature is available http://llvm.org/docs/Passes.html with options such as -dce: Dead Code Elimination, -adce: Aggressive Dead Code Elimination.
One way to know for sure what is included is checking the assembly output using -emit-assembly option in the swift compiler and review the output, or opening the binary in a disassembler such as Hopper ( http://www.hopperapp.com/download.html )
My company makes a static library for iOS apps. One annoying step for developers is that they have to manually link against all the required frameworks that the library uses, and failing to do so leads to somewhat confusing compiler errors.
I would have previously thought this wasn't possible, but the company Chartboost claims to automatically link against non-default frameworks like AdSupport and StoreKit. Based on my testing in their sample app (available from the linked page), so far this appears to be the case (Even when disabling "Enable Modules" and "Link Frameworks Automatically" in the app that links against the static library).
Is there some way to enable this feature when creating a static library? I've tried enabling modules and the "Link Frameworks Automatically" LLVM options in Xcode, but so far haven't been able to get it working.
There's a piece of code called CBDynamicallyLoadedDependencies that calls dlopen() on the appropriate system library before making the function or method call.
My original answer wasn't correct. the dlopen() call is just in the x86 code. On the device, it's something different, but my ARM assembly isn't strong enough to figure it out. All I can say is that there's a piece of code that's acting as a trampoline to the desired functions and that references the system library files (like /System/Library/Frameworks/AdSupport.framework/AdSupport).
But the point is that it's not a simple project trick that makes it work normally. There's internal code involved.
They might use modules you mentioned and #import instead of #import, which should make the libraries link automatically.
For reference, check this question.
This might not be what you're looking for, but if you don't yet support Cocoapods, I would strongly advise taking a look:
http://cocoapods.org/
(Edit: Cocoapods is essentially linked to Xcode. Other IDEs will need another solution.)
You can advertise Cocoapods to developers as the "easy" way to work with your library, and the manual method as...well, the manual method. ;)
I'm not aware of any industry resistance to Cocoapods, so I don't see a downside to supporting it, and it does solve the problem you're talking about (albeit in a roundabout sort of way).
Also I've found Chartboost VERY developer-friendly. You might even reach out to them and ask.
I'm developing an iOS SDK that integrates other SDKs (Facebook SDK 3.5, for example).
To prevent collisions and allow my customers to import those SDKs as well, I want to rename all of the classes/enums in my code (for example, rename FBSession to RDFBSession, etc).
Is there an easy way to do this instead of going class-by-class and using Xcode's rename feature?
Apple provide a command-line tool called tops(1) that is designed for scripting large-scale code refactoring (renaming C functions, Objective-C methods, classes, and other tokens):
tops -verbose replace "FBSession" with "RDFBSession" Sources/*.[hm]
If you have a lot of replacements, you can put all of the replace... commands into a file that you pass with the -scriptfile option. The man page has more information on the more complex commands/options (and examples).
Xcode also offers textual Search and Replace. This will be faster than individual refactors, but it is ultimately less automated. You can make the step by step refactoring faster by first minimizing the project to the relevant dependencies/sources (if possible).
However, renaming the declarations in a library will not alter the symbol names of its associated binary. If it is distributed with a binary, then renaming will just result in linker errors or (in some cases) runtime errors.
The best idea if you need to use a 3rd party library which your clients might also use is to simply inform them they need to link the library with their app, then publish the version(s) the current release supports so they know they have some extra testing if they go too far ahead with some libraries.
I think that a better approach than simply renaming your classes would be to download Facebook's open source code, rename the classes there and compile a new static library with a set of renamed header files. Then you can be sure that no collisions occur and that you're using symbols that you named yourself.
I must warn you though - working like this may make updating the SDK a nightmare regardless of how you tackle this specific issue.