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I have a C lib and dll file from windows application. No source code with me. Is it possible to use that in an IOS application.

I have seen mixed responses and am confused. If we have source code , i think we need to create dylib and then we can use the same after including relevant header file.

Please share any expert ideas to guide me in right direction. Appreciate your help .

  • mia
mia
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Dynamic Libraries are not permitted on iOS to begin with, but above that, the DLL file format is not recognized by Darwin or the underlying XNU Kernel at all, as the binary format is different.

Windows APIs are not usable on the Darwin OS either (Both Mac OS X and iOS are wrappers around the basic Darwin OS). You will need to rewrite the code from the DLL to use the POSIX and/or Objective-C APIs and compile it as a static library to use it.

Aditya Vaidyam
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  • Thanks for the details. I saw details for .a files as Version 1.5 Mac OSX 64/32-bit Universal Binaries (for Intel, Snow Leopard/10.6 or later) of OpenJPEG library and codecs at http://code.google.com/p/openjpeg/downloads/list . Can i use that in IOS ? Basically my need is to use OPENJPEG2000 lib and decompress an image in IOS. Thanks for your help – mia May 23 '12 at 06:31
  • Of course, if it works on Mac OS X and is a static library, it should work for iOS as well. If they provide the source code to it, you could manually recompile it (wouldn't take that long to do so) and it would run just dandy. – Aditya Vaidyam May 23 '12 at 07:19
  • http://stackoverflow.com/questions/9580420/build-openjpeg-for-iphone-with-configure-and-make would help you out. – Aditya Vaidyam May 23 '12 at 07:20
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You need to get a iOS compatible library, no other way around it. There are several reasons:

  • iOS doesn't support DLLs as they are windows format, but moreover, you can't use any dynamic library on iOS, as Apple restricts it.
  • DLLs are usually for intel CPUs, while iOS devices have ARM CPUs.
  • Most dlls are calling windows APIs - are you sure this one's not?
MByD
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  • Incorrect; DLLs themselves are cross-platform: their binary format is different however. In this case, iOS is ARM-only, so a DLL from an intel CPU would not work. – Aditya Vaidyam May 10 '12 at 04:28
  • @Galaxas0 - do you say Mac OSX (lets say on intel CPU) is able to load DLLs and use them? This is new to me – MByD May 10 '12 at 04:32
  • Thanks for the answer. I am trying to do OpenJpeg2000 decode and encode. This dll is for the same. In that case i dont think it will be using Windows APIs. So in case if i get the source code ( as it is open source ) , i can compile and use in IOS rt? – mia May 10 '12 at 06:07
  • @mia - it is probably possible, but it might be complicated. Worth the shot though. – MByD May 10 '12 at 06:08
  • Mac OS X and iOS are based upon the same underpinnings: Darwin and the XNU Kernel. The Mac OS X and iOS names refer to the interaction style and interface layer COMBINED with the XNU Kernel and Darwin OS. Even on an Intel CPU, Darwin cannot read DLL binaries. Read more about the Mach-O binary format, if you need more information. – Aditya Vaidyam May 10 '12 at 06:09
  • @mia You would need to specifically target a static library (.a) while recompiling it on Mac OS X, for the ARMv6 platform (to run on iOS). – Aditya Vaidyam May 10 '12 at 06:11
  • @Galaxas0 - I don't understand what are you trying to say, I just listed a few reasons why it may not work. Could you please elaborate and explain to me with which part of my answer you disagree? Thanks a lot. – MByD May 10 '12 at 06:12
  • Oh no, I meant to agree with your answer, just that there were discrepancies in the way you explained it: 'windows format' should probably be 'Portable Executable (Windows) binaries', and 'usually for intel CPUs' should be 'usually compiled for intel CPUs', but your answer is right. My bad if I came across wrong :] EDIT: Upvoted your answer, too :D – Aditya Vaidyam May 10 '12 at 06:13
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You are going to have to recompile it as a static library (.a file). Apple doesn't allow dynamic libraries except for their own frameworks (so you can't compile it as a dylib).

borrrden
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No. If you all you have is a compiled binary DLL, there is no way to use it on iOS. Unless you happen to have an ARM DLL for the upcoming Windows 8, your DLL contains either x86 or x86-64 machine code (or maybe IA64 if you have a lot of money), which absolutely will not run on iOS devices, which are all ARM architectures. Plus many more reasons.

If you have the source code, you can recompile it for iOS, either directly into your app, as a static library that can be linked in with your app, or as a dynamic library as part of a framework. But in all cases, you need to recompile it from source code using the iOS compiler.

Adam Rosenfield
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  • Incorrect; DLL files themselves are not dynamic libraries loadable by the XNU Kernel or Darwin (the Mac OS X underlying OS), and dynamic libraries themselves are not permitted on iOS. – Aditya Vaidyam May 10 '12 at 04:30
  • I never said DLLs were loadable by the XNU Kernel or Darwin. I'm pretty sure that iOS does have dynamic libraries -- when you weak link against a framework, the OS tries to load that framework at runtime. Using weak frameworks is a common way of providing optional functionality on devices with more recent versions of the OS. But I think you're right on that last part -- AFAIK, Apple doesn't let you create your own dynamic libraries or frameworks, you can only use the ones they provide. – Adam Rosenfield May 10 '12 at 23:18
  • My bad then, maybe 'incorrect' was a bit harsh. And you are correct- technically speaking, dynamic libraries do exist. The reason Apple won't let you load them is because they may be malicious (think the recent Flashback trojan), so Apple runs `otool -l` on all binaries and checks them for any non-Apple dylibs or .frameworks. – Aditya Vaidyam May 10 '12 at 23:53