1.判断有无sim卡 http://www.2cto.com/kf/201306/223744.html
2.Let's Build xxx (如nsobject)系列- by Mike Ash,可以用做学习（理解很多ios内部的实现机制），很不错  https://www.mikeash.com/pyblog/friday-qa-2013-02-08-lets-build-key-value-coding.html
3.method swizz http://www.cocoachina.com/applenews/devnews/2014/0225/7880.html
4.ios中的消息传递机制 http://www.cocoachina.com/applenews/devnews/2013/1216/7543.html
5.google地图编码api官方介绍 https://developers.google.com/maps/documentation/geocoding/?hl=zh-CN
6.ios版本检测 http://www.cnblogs.com/weilaikeji/p/3331772.html