Xcode构建失败“架构x86_64未定义的符号”

一个Xcode初学者的问题:

这是我第一次使用Xcode 4.6.3。

我试图写一个非常简单的控制台程序，搜索配对的BT设备，并将它们打印到NSLog。

它会生成以下错误:

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_IOBluetoothDevice", referenced from:
      objc-class-ref in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我疯狂地搜索。常见的问题应该是对文件的引用，其中只有头文件被导入，链接器没有找到任何实现(*.m-file)。IOBluetooth库是一个标准框架，就像基础框架一样。

我在上面的陈述中遗漏了什么?

我还尝试为32位机器构建它(构建再次失败)。这显然是一个链接器错误，但我不知道，它与什么有关，除了有一个问题，找到IOBluetoothDevice的实现，在x86和x64架构上，而头文件是从一个标准包含的框架，称为IOBluetooth?

供你参考，我的主要代码是main。m”:

#import <Foundation/Foundation.h>
#import <IOBluetooth/objc/IOBluetoothDevice.h>          // Note the import for bluetooth
#import <IOBluetooth/objc/IOBluetoothDeviceInquiry.h>   // Note the import for bluetooth


int main(int argc, const char * argv[])
{
    @autoreleasepool {
        IOBluetoothDevice *currentDevice;
        NSArray *devices = [ IOBluetoothDevice pairedDevices];


        for (id currentDevice in devices){
          NSLog(@"%i : %@",[ currentDevice classOfDevice ], [ currentDevice name ]);    
        }
    }
    return 0;
}

谢谢你的任何帮助或指点正确的方向。

当前回答

If you're getting this error when trying to link to a C file, first double check the function names for typos. Next double check that you are not trying to call a C function from a C++ / Objective-C++ environment without using the extern C {} construct. I was tearing my hair out because I had a class that was in a .mm file which was trying to call C functions. It doesn't work because in C++, the symbols are mangled. You can actually see the concrete symbols generated using the nm tool. Terminal to the path of the .o files, and run nm -g on the file that is calling the symbol and the one that should have the symbol, and you should see if they match up or not, which can provide clues for the error.