我也有同样的问题。我尝试了答案列表中的每一种方法，但最终我的问题是: 我正在使用openCV，所以我需要在我的代码中结合c++代码。要做到这一点，你应该将使用objective-c和c++的文件更改为.mm 我没有改变一个文件，这个文件没有连接到c++代码，但我必须改变它。

目标中可能缺少一些类。这通常发生在你重命名/删除/添加新的类文件到你的项目。若要修复，请将新添加的类添加到某些目标。

在Project Navigator中选择类(右侧栏)，打开Utilities侧栏(右侧栏)，从Utilities中选择File Inspector (File like icon)，在Target Membership选项卡下勾选你的目标。这都是为了避免“删除引用”，并再次添加“添加到目标”的技巧。

所以:选择Class -> Utilities (File Inspector) -> Target Membership ->勾选你想要的目标。

常见的原因

导致“架构armv7中未定义的符号”的常见原因有:

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 the Library 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. 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. 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.

最初的回答:

您没有链接到正确的libz文件。如果你右键点击该文件并在finder中显示它的路径应该在iOS sdk文件夹中的某个地方。这是我的例子

/开发/平台/ iPhoneOS.platform /开发/ sdk / iPhoneOS4.3.sdk / usr / lib

我建议删除引用，然后在目标的构建阶段Link Binary With Libraries部分重新添加它。

别名通常不包含链接到当前版本的版本标识符，在本例中为libz。Dylib链接到libz.1.2.5.dylib。使用基本别名，而不是版本化的别名。

If you're building from Unity3D 5 and also using a Prime31 plugin and you're getting this error it's probably due to a duplicate .dll. If you look through your warnings in Unity's editor one of them will tell you this and warn that it could cause build errors. To see if this is the case, type P31 in your project search field and it should pop right up, maybe even more than one. The duplicate's will have a ' 1' at the end of the file name. This is probably caused from updating the plugin in editor via the store or the Prime31 menu tab.

对我来说，问题是我忘记在.m(实现)中为我的常量设置值

file const kFooKey = @"Foo";