查了一下 arc和c++0x是新功能 我猜的没错 呵呵 Default Compiler The default compiler for iOS development in Xcode 4.2 is LLVM 3.0. Compared with the GCC compiler that was the default in Xcode 4.0 and the LLVM-GCC compiler in Xcode 4.1, LLVM provides better code generation and optimization than GCC, along with newer language support than LLVM-GCC, including support for ARC in Objective-C and for the new C++ standard, C++0x.