关于 undefined symbols for architecture armv7 referenced from 问题

今天在调用公司其它人写的静态库的时候，编译一直无法通过一直报错 undefined symbols for architecture armv7 referenced from。

最后发现是在制作静态库的时候，只是把文件添加到了工程。

但是compil sources里面默认没有添加的，需要我们手动去添加资源文件，然后就解决了。

下面附带stackoverflow有人分析的几个原因

http://stackoverflow.com/questions/6429494/undefined-symbols-for-architecture-armv7

The common causes for "Undefined symbols for architecture armv7" are:

1. You import a header and do not link against the correct library. This is common, especially for headers for libraries like QuartzCore since it is not included in projects by default. To resolve:

   • Add the correct libraries in the Link Binary With Libraries section of the Build Phases.

   • If you want to add a library outside of the default search path you can include the path in theLibrary Search Paths value in the Build Settings and add 
     -l{library_name_without_lib_and_suffix} (eg. for libz.a use -lz) to the Other Linker Flags section of Build Settings.
     
     

2. You copy files into your project but forgot to check the target to add the files to. To resolve:

   • Open the Build Phases for the correct target, expand Compile Sources and add the missing .m files. If this is your issue please upvote Cortex's answer below as well.
     
     

3. You include a static library that is built for another architecture like i386, the simulator on your host machine. To resolve:

   • If you have multiple library files from your libraries vendor to include in the project you need to include the one for the simulator (i386) and the one for the device (armv7 for example).

   • Optionally, you could create a fat static library that contains both architectures.