另一个可能导致“未定义符号”链接错误的原因是试图从.mm文件调用C函数。在这种情况下，您需要使用extern“C”{…}当您导入头文件时。

从objective - c++调用C-Function链接器错误

我遇到了一个PJSIP库的问题，

在项目中的其他链接器标志中尝试了以下操作，并能够解决错误: 框架 基金会 框架 UIKit

上面的链接标志用于Siphone项目在github上。这些设置将帮助您解决与c++库链接相关的问题。

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";

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。

回到你的项目，点击Build phases, Compile sources, Add GameCenterManager。M到列表上。

如果你正在处理iOS5升级，我发现要编译一个目标4.3的项目，我可以将libz.1.2.3重命名。dynlib的项目导航到libz.1.2.5。Dynlib和它编译。

我的iPhoneOS50SDK/usr/lib文件夹没有libz.1.2.3。Dynlib——不知道它是测试版还是自然升级。