在我一直在做的项目中，我们必须将 Cocoa 通知从 C++ 子项目发送到它上面的主项目。为此，我们构建了一个映射来充当通知的 userInfo 字典的键值对存储。
在其中一个项目中，以下代码编译得很好：
std::map<std::string, std::string> *userInfo = new std::map<std::string, std::string>;
char buffer[255];
sprintf(buffer, "%i", intValue1);
userInfo->insert(std::pair<std::string, std::string>("intValue1", std::string(buffer)));
sprintf(buffer, "%i", intValue2);
userInfo->insert(std::pair<std::string, std::string>("intValue2", std::string(buffer)));
if(condition)
userInfo->insert(std::pair<std::string, std::string>("conditionalValue", "true"));
PostCocoaNotification("notificationName", *userInfo);
但是，当它被复制到另一个子项目中的相同文件中时，编译器会在 userInfo->insert 调用中抛出以下内容：
"Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'"
..它找不到 PostCocoaNotification 的功能：
No matching function for call to 'PostCocoaNotification'
此外，它会在系统标头中引发以下错误：
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:73:11: Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:74:11: Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_pair.h:73:11: Implicit instantiation of undefined template 'std::basic_string<char, std::char_traits<char>, std::allocator<char> >'
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/usr/include/c++/4.2.1/bits/stl_tree.h:1324:13: Cannot initialize a parameter of type '_Link_type' (aka '_Rb_tree_node<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > *') with an rvalue of type '_Const_Link_type' (aka 'const _Rb_tree_node<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > *')
我不知道我做了什么导致这种混乱，尤其是当代码在另一个子项目中运行得非常好（成功发送通知）时。对此问题的任何见解都将受到欢迎。