blocks|key|875425|text|你知道苹果的参考页面动态图书馆规划主题吗？它应该涵盖你所需要的大部分内容。请注意，有一个在程序启动时无条件加载的共享库和按需加载的动态加载库(bundle，IIRC)，这两个库在MacOS+X上与在Linux或Solaris上的等效库略有不同。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|875426|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/DynamicLibraries/index.html^0|A|9|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Are you aware of the Apple reference page <a href="http://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/DynamicLibraries/index.html" rel="nofollow noreferrer">Dynamic Library Programming Topics</a>? It should cover most of what you need. Be aware that there a shared libraries that get loaded unconditionally at program startup and dynamically loaded libraries (bundles, IIRC) that are loaded on demand, and the two are somewhat different on MacOS X from the equivalents on Linux or Solaris.

blocks|key|217278|text|您可能需要确保您构建的动态库有一个导出的符号文件，该文件列出了应该从库导出的内容。这只是一个简单的符号列表，每行一个，可以导出。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|217279|此外，在构建动态库时，它将获得嵌入其中的安装名称，默认情况下，该名称是生成该库的路径。随后，任何链接到它的东西都会首先在指定的路径上查找它，然后才在手册页中的手册页中搜索一组(小的)默认路径。|offset|length|217280|如果要将这个库放在可执行文件的旁边，您应该调整它的安装名称以引用它。只要在谷歌上搜索“安装名称”，就会发现大量的信息。|217281|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/documentation/Darwin/Reference/ManPages/man1/dyld.1.html|1^0|0|22|3|0|27|3|1|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@$D|S|E|T|1|U]|$D|V|E|W|1|X]]|A|$]]|$1|F|3|G|5|6|7|Y|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]|P|$5|K|L|M|A|$N|O]]]]

You probably need to ensure that the dynamic library you build has an exported symbols file that lists what should be exported from the library. It's just a flat list of the symbols, one per line, to export.

Also, when your dynamic library is built, it gets an install name embedded within it which is, by default, the path at which it is built. Subsequently anything that links against it will look for it at the specified path first and only afterwards search a (small) set of default paths described under <code>DYLD_FALLBACK_LIBRARY_PATH</code> in the <a href="http://developer.apple.com/documentation/Darwin/Reference/ManPages/man1/dyld.1.html" rel="noreferrer" title="dyld(1) man page"><code>dyld(1)</code> man page</a>.

If you're going to put this library next to your executables, you should adjust its install name to reference that. Just doing a Google search for "install name" should turn up a ton of information on doing that.

blocks|key|217330|text|不幸的是，以我的经验，苹果的文档是过时的，多余的，并且丢失了很多你通常需要的公共信息。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|217331|我在我的网站上写了很多东西，我不得不让FMOD+(声音API)和我们在uni开发的跨平台游戏一起工作。这是一个奇怪的过程，我很惊讶苹果没有在他们的开发者文档上添加更多的信息。|217332|不幸的是，像微软一样“邪恶”，他们实际上做得更好，他们的发展与文档(这是来自苹果福音)。|217333|我认为，基本上，您没有做的是在您已经编译了您的.app包。然后，您需要在可执行的二进制/MyApp.app/contents/MacOS/MyApp上运行一个命令，以更改可执行文件查找其库文件的位置。您必须创建一个可以运行脚本的新构建阶段。我不会再解释这个过程了，我已经在这里做了深入的研究：|217334|http://brockwoolf.com/blog/how-to-use-dynamic-libraries-in-xcode-31-using-fmod|offset|length|217335|希望这能有所帮助。|217336|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|0|0|26|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@$J|Z|K|10|1|11]]|A|$]]|$1|L|3|M|5|6|7|12|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|O|$P|$5|Q|R|S|A|$T|I]]]]

Unfortunately, in my experience Apple's documentation is antiquated, redundant and missing a LOT of common information that you would normally need.

I wrote a bunch of stuff on this on my website where I had to get FMOD (Sound API) to work with my cross platform game that we developed at uni. Its a weird process and I'm surprised that Apple do not add more info on their developer docs.

Unfortunately, as "evil" as Microsoft are, they actually do a much better job of looking after their devs with documentation ( this is coming from an Apple evangelist ).

I think basically, what you are not doing is AFTER you have compiled your .app Bundle. You then need to run a command on the executable binary /MyApp.app/contents/MacOS/MyApp in order to change where the executable looks for its library file. You must create a new build phase that can run a script. I won't explain this process again, I have already done it in depth here:

<a href="http://brockwoolf.com/blog/how-to-use-dynamic-libraries-in-xcode-31-using-fmod" rel="noreferrer">http://brockwoolf.com/blog/how-to-use-dynamic-libraries-in-xcode-31-using-fmod</a>

Hope this helps.

blocks|key|1216527|text|Mac上的动态链接，一个很小的例子|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1216528|步骤：|1216529|创建包含mymod.o的库libmylib.dylib|ordered-list-item|1216530|编译并链接一个调用它的"callmymod“|1216531|使用DYLD_LIBRARY_PATH和DYLD_PRINT_LIBRARIES从callmymod调用mymod|1216532|问题:您“只是”想要创建一个库供其他模块使用。然而，有一堆令人望而生畏的程序--+gcc、ld、macosx+libtool、dyld+--有数以百万计的选项，一些腐朽的堆肥，以及MacOSX和Linux的区别。有大量的手册页(我数了一下10.4.11+ppc中的7679+%2B+1358+%2B+228+%2B+226行)，但是没有太多的例子，或者使用“告诉我你在做什么”模式的程序。|1216533|(理解中最重要的是为自己做一个简单的概述:画一些图片，运行一些小例子，向其他人解释)。|1216534|背景：苹果OverviewOfDynamicLibraries，图书馆|offset|length|1216535|步骤1，创建libmylib.dylib+--|1216536|mymod.c:
++++#include+<stdio.h>
++++void+mymod(+int+x+)
++++{
++++++++printf(+"mymod:+%25d\n",+x+);
++++}
gcc+-c+mymod.c++#+->+mymod.o
gcc+-dynamiclib+-current_version+1.0++mymod.o++-o+libmylib.dylib
++++#+calls+libtool+with+many+options+--+see+man+libtool
++++#+-compatibility_version+is+used+by+dyld,+see+also+cmpdylib

file+libmylib.dylib++#+Mach-O+dynamically+linked+shared+library+ppc
otool+-L+libmylib.dylib++#+versions,+refs+/usr/lib/libgcc_s.1.dylib|code-block|syntax|javascript|1216537|第2步，编译和链接callmymod+--|1216538|callmymod.c:
++++extern+void+mymod(+int+x+);
++++int+main(+int+argc,+char**+argv+)
++++{
++++++++mymod(+42+);
++++}
gcc+-c+callmymod.c
gcc+-v+callmymod.o+./libmylib.dylib+-o+callmymod
++++#+==+gcc+callmymod.o+-dynamic+-L.+-lmylib
otool+-L+callmymod++#+refs+libmylib.dylib
nm+-gpv+callmymod++#+U+undef+_mymod:+just+a+reference,+not+mymod+itself|1216539|第三步，运行callmymod链接到libmylib.dylib+--|1216540|export+DYLD_PRINT_LIBRARIES=1++#+see+what+dyld+does,+for+ALL+programs
./callmymod
++++dyld:+loaded:+libmylib.dylib+...
++++mymod:+42

mv+libmylib.dylib+/tmp
export+DYLD_LIBRARY_PATH=/tmp++#+dir:dir:...
./callmymod
++++dyld:+loaded:+/tmp/libmylib.dylib+...
++++mymod:+42

unset+DYLD_PRINT_LIBRARIES
unset+DYLD_LIBRARY_PATH|1216541|这就结束了一个很小的例子，希望它能帮助理解步骤。|1216542|(如果您经常这样做，请参阅GNU+Libtool，它是macs上的glibtool，以及SCons。)|1216543|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/DynamicLibraries/100-Articles/OverviewOfDynamicLibraries.html|1|http://en.wikipedia.org/wiki/Dynamic_library|2|http://en.wikipedia.org/wiki/Libtool|3|http://www.scons.org/^0|0|0|0|0|0|0|0|3|S|0|W|3|1|0|0|0|0|0|0|0|0|D|B|2|18|5|3|0^^$0|@$1|2|3|4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1R|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|1S|8|@]|9|@]|A|$]]|$1|I|3|J|5|F|7|1T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|1U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1V|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1W|8|@]|9|@$Q|1X|R|1Y|1|1Z]|$Q|20|R|21|1|22]]|A|$]]|$1|S|3|T|5|6|7|23|8|@]|9|@]|A|$]]|$1|U|3|V|5|W|7|24|8|@]|9|@]|A|$X|Y]]|$1|Z|3|10|5|6|7|25|8|@]|9|@]|A|$]]|$1|11|3|12|5|W|7|26|8|@]|9|@]|A|$X|Y]]|$1|13|3|14|5|6|7|27|8|@]|9|@]|A|$]]|$1|15|3|16|5|W|7|28|8|@]|9|@]|A|$X|Y]]|$1|17|3|18|5|6|7|29|8|@]|9|@]|A|$]]|$1|19|3|1A|5|6|7|2A|8|@]|9|@$Q|2B|R|2C|1|2D]|$Q|2E|R|2F|1|2G]]|A|$]]|$1|1B|3|-4|5|6|7|2H|8|@]|9|@]|A|$]]]|1C|$1D|$5|1E|1F|1G|A|$1H|1I]]|1J|$5|1E|1F|1G|A|$1H|1K]]|1L|$5|1E|1F|1G|A|$1H|1M]]|1N|$5|1E|1F|1G|A|$1H|1O]]]]

Dynamic linking on Mac OS X, a tiny example
Steps:
<ol>
<li>create a library libmylib.dylib containing mymod.o</li>
<li>compile and link a &quot;callmymod&quot; which calls it</li>
<li>call mymod from callmymod, using DYLD_LIBRARY_PATH and DYLD_PRINT_LIBRARIES</li>
</ol>
Problem: you &quot;just&quot; want to create a library for other modules to use.
However there's a daunting pile of programs -- gcc, ld, macosx libtool, dyld --
with zillions of options, some well-rotted compost, and differences between MacOSX and Linux.
There are tons of man pages (I count 7679 + 1358 + 228 + 226 lines in 10.4.11 ppc)
but not much in the way of examples, or programs with a &quot;tell me what you're doing&quot; mode.
(The most important thing in understanding is to make a simplified
OVERVIEW for yourself: draw some pictures, run some small examples,
explain it to someone else).
Background: <a href="https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/DynamicLibraries/100-Articles/OverviewOfDynamicLibraries.html" rel="nofollow noreferrer">apple OverviewOfDynamicLibraries</a>,
<a href="http://en.wikipedia.org/wiki/Dynamic_library" rel="nofollow noreferrer">Wikipedia Dynamic_library</a>
<hr />
Step 1, create libmylib.dylib --
<pre><code>mymod.c:
 #include &lt;stdio.h&gt;
 void mymod( int x )
 {
 printf( &quot;mymod: %d\n&quot;, x );
 }
gcc -c mymod.c # -&gt; mymod.o
gcc -dynamiclib -current_version 1.0 mymod.o -o libmylib.dylib
 # calls libtool with many options -- see man libtool
 # -compatibility_version is used by dyld, see also cmpdylib

file libmylib.dylib # Mach-O dynamically linked shared library ppc
otool -L libmylib.dylib # versions, refs /usr/lib/libgcc_s.1.dylib
</code></pre>
<hr />
Step 2, compile and link callmymod --
<pre><code>callmymod.c:
 extern void mymod( int x );
 int main( int argc, char** argv )
 {
 mymod( 42 );
 }
gcc -c callmymod.c
gcc -v callmymod.o ./libmylib.dylib -o callmymod
 # == gcc callmymod.o -dynamic -L. -lmylib
otool -L callmymod # refs libmylib.dylib
nm -gpv callmymod # U undef _mymod: just a reference, not mymod itself
</code></pre>
<hr />
Step 3, run callmymod linking to libmylib.dylib --
<pre><code>export DYLD_PRINT_LIBRARIES=1 # see what dyld does, for ALL programs
./callmymod
 dyld: loaded: libmylib.dylib ...
 mymod: 42

mv libmylib.dylib /tmp
export DYLD_LIBRARY_PATH=/tmp # dir:dir:...
./callmymod
 dyld: loaded: /tmp/libmylib.dylib ...
 mymod: 42

unset DYLD_PRINT_LIBRARIES
unset DYLD_LIBRARY_PATH
</code></pre>
That ends one tiny example; hope it helps understand the steps. 
(If you do this a lot, see <a href="http://en.wikipedia.org/wiki/Libtool" rel="nofollow noreferrer">GNU Libtool</a>
which is glibtool on macs,
and <a href="http://www.scons.org" rel="nofollow noreferrer">SCons</a>.)

I'm building few command-line utilities in Xcode (plain C, no Cocoa). I want all of them to use my customized version of libpng, and I want to save space by sharing one copy of the library among all executables (I don't mind re-distributing <code>.dylib</code> with them).

Do I need to do some magic to get libpng export symbols?

Does "Link Binary With Libraries" build phase link statically? 

Apple's docs mention loading of libraries at run time with <code>dlopen</code>, but how I can make Xcode create executable without complaining about missing symbols?

<hr>

I think I've figured it out:

<ul>
<li>libpng wasn't linking properly, because I've built 32/64-bit executables and 32-bit library. Build settings of the library and executables must match.</li>
<li>libpng's config.h needs to have tons of defines like <code>#define FEATURE_XXX_SUPPORTED</code></li>
<li>"Link Binary With Libraries" build phase handles dynamic libraries just fine, and <code>DYLD_FALLBACK_LIBRARY_PATH</code> environmental variable is neccessary for loading <code>.dylib</code>s from application bundle.</li>
</ul>

How do I create a dynamic library (dylib) with Xcode?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在用Xcode构建几个命令行实用程序(普通C，没有Cocoa)。我希望它们都使用我定制的libpng版本，并且我希望通过在所有可执行文件中共享一个库副本来节省空间(我不介意与它们重新分发.dylib )。我需要做一些魔术才能得到导出符号吗？“用库链接二进制”静态地构建阶段链接吗？苹果的文档提到了在运行时用dlope...

问如何使用Xcode创建动态库(dylib)？
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问如何使用Xcode创建动态库(dylib)？EN