NSstring*json=@"\"s\":{\"n\":\"刹车\"}";
NSData* alarmInfoData = [json dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary * alarmInfoDic =[NSJSONSerialization JSONObjectWithData:alarmInfoData options:NSJSONReadingMutableLeaves error:nil];
原文：http://blog.csdn.net/lcxihonglei/article/details/46009201