git : refusing to merge unrelated histories

用 cocoaPods 创建了一个demo 程序, 在向 github 上传的时候, push 报错
! [rejected] master -> master (non-fast-forward)
error: failed to push some refs to ‘https://github.com/name/XXXX.git’

google 下,解决办法是:

$ git fetch origin
$ git merge origin branch

出现问题:
merge: origin - not something we can merge

或者用:

$ git pull origin branch

出现错误:
fatal: Couldn’t find remote ref branch

换一种方式, git pull 一下, 报错:
* branch master -> FETCH_HEAD
fatal: refusing to merge unrelated histories

还是有问题, 此时是因为: 他们是两个不同的项目，要把两个不同的项目合并，git需要添加一句代码.

$ git pull origin master --allow-unrelated-histories

然后我们在执行:

$ git add .
$ git commit -m "xxx"
$ git push origin master

大功告成…