在ubuntu Linux上安装Objective-C的编译环境

因为ubuntu的仓库中已经包含了gnustep，所以可以用以下的命令快速地安装
1. sudo apt-get install gnustep
2. sudo apt-get install gnustep-devel

解决错误(Broken packages)：
    Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming.
    The following information may help resolve the situation:

    The following packages have unmet dependencies:
    gnustep-devel: Depends: gorm.app but it is not installable
    E: Broken packages

解决：
in /etc/apt/sources.list – add urls like:

deb http://mirror.aarnet.edu.au/debian/ squeeze main
deb-src http://mirror.aarnet.edu.au/debian/ squeeze main

Do:
sudo apt-get update
sudo apt-get -t gnustep install gorm.app
sudo apt-get install gnustep-devel