https://purengom.com/2011/05/27/iphone%ec%9d%98-%eb%b0%b0%ed%84%b0%eb%a6%ac%eb%a5%bc-%ec%a0%88%ec%95%bd%ed%95%98%eb%8a%94-%eb%aa%87%ea%b0%80%ec%a7%80-%eb%b9%84%ea%b2%b0/