今天在合并项目代码时，.DS_Store和.xcuserstate文件冲突无法合并。需要移除忽略.DS_Store和.xcuserstate文件。
1.打开终端，切换到项目路径, 输入 cd 项目路径 ,
2.创建.gitignore文件,此文件可创建需要忽略的类型文件,执行 vim .gitignore,输入
.DS_Store*.xcuserstate
按ESC，在输入:wq保存退出
3.在命令行输入
git rm --cached *xcuserstate
git rm ---cached .DS_Store
按：再按wq退出编辑
4.执行
$ git add .gitignore
$ git commit -m "Remove and ignore .xcuserstate and .DS_Store files."
添加并提交文件
5.打开项目，解决其他项目文件冲突，合并代码
合并时可能会报
error: merge is not possible because you have unmerged files.
hint: Fix them up in the work tree, and then use 'git add/rm '
hint: as appropriate to mark resolution and make a commit.
fatal: Exiting because of an unresolved conflict.
执行
git add .
git commit -a -m "add ."
git pull origin master
git merge origin/master
成功解决!
参考资料：
https://stackoverflow.com/questions/21868857/removing-xcuserstate-and-ds-store-files-from-git
http://www.jianshu.com/p/4f69c79b295f
