1.查看端口是否被占用
sudo lsof -i -n
2.用终端运行xampp，查看具体的错误
sudo su
/Applications/XAMPP/xamppfiles/xampp start
多半是这个问题：
XAMPP: Starting Apache...fail.
XAMPP: Another web server is already running.
解决办法：
sudo apachectl stop
// This command killed Apache server that was pre-installed on MAC OS X.