//json数组
let data=[{"userList":[
{"id":"0c870834932347bb","phone":"9999","uname":"9999","utype":"0","upassword":"9999","ipaddress":"3","utime":"2017-06-30 14:50:27"},{"id":"0cdf458d93bc4b10","phone":"54321","uname":"54321","upassword":"54321","ipaddress":"1","utime":"2017-06-29 19:11:42"},{"id":"085fe33134f44f10","phone":"1111","uname":"1111","upassword":"1111","ipaddress":"4","utime":"2017-06-29 15:44:05"},{"id":"1584f6f7f4e24597","phone":"1234","uname":"1234","upassword":"1234","ipaddress":"2","utime":"2017-06-29 13:08:06"}],"resultCode":"999"}]
let jsonArr = try! JSONSerialization.jsonObject(with:data!,options:JSONSerialization.ReadingOptions.mutableContainers) as! [[String: Any]]                
for json in jsonArr {
    let code1=(json["resultCode"])as! String
    if code1=="999"{
        print("连接成功")
        //userList提取后code2为NSArray的数组类型 
        let code2:NSArray=(json["userList"])as! NSArray
        //code3一个NSDictionary类型
        let code3:NSDictionary=(code2[0])as! NSDictionary//index为在code2中第index个
        (code3["id"])as! String  //这个输出为“0c870834932347bb” 
    } 
}