cocoapods 更新失败 bad response Not Found 404 (http://ruby.taobao.org/specs.4.8.gz)

ERROR:  Could not find a valid gem 'cocoapods' (>= 0), here is why:

          Unable to download data from http://ruby.taobao.org/ - bad response Not Found 404 (http://ruby.taobao.org/latest_specs.4.8.gz)

解决办法：换源地址

1. gem sources --remove http://ruby.taobao.org/ //移除原文件地址 

2.  gem sources -a https://ruby.taobao.org/   //添加新文件地址

3. gem sources -l    //查看源文件地址是否正确

4. sudo gem install cocoapods    //更新