https://blog.faceutil.com/2017/03/29/iosandroid-%ec%9d%b8%ea%b7%b8%eb%a0%88%ec%8a%a4ingress-%ec%a0%84%ec%84%b8%ea%b3%84%eb%a5%bc-%eb%ac%b4%eb%8c%80%eb%a1%9c-%ed%95%9c-%ed%98%84%ec%8b%a4-%eb%95%85%eb%94%b0%eb%a8%b9%ea%b8%b0-%ec%a0%84/