1、python2 出现问题的解决办法：
sudo C_INCLUDE_PATH=/Applications/Xcode.app/Contents/Developer/Platforms/AppleTVSimulator.platform/Developer/SDKs/AppleTVSimulator.sdk/usr/include/libxml2:/Applications/Xcode.app/Contents/Developer/Platforms/AppleTVSimulator.platform/Developer/SDKs/AppleTVSimulator.sdk/usr/include/libxml2/libxml:/Applications/Xcode.app/Contents/Developer/Platforms/AppleTVSimulator.platform/Developer/SDKs/AppleTVSimulator.sdk/usr/include pip install Scrapy
问题解决
2、在我用python3 安装lxml的时候出现了同样的错误：
解决办法是：
输入命令：
xcode-select --install
然后再输入命令：
python3 setup.py install
安装完成