1.http://blog.csdn.net/dangyalingengjia/article/details/77964582
2.http://www.cocoachina.com/ios/20170915/20580.html
3.http://mp.weixin.qq.com/s/iJqBdAepdC46K16tdB60Wg
4.http://mp.weixin.qq.com/s/2dCavLv8IwTrgq5zU0RSaA