结构数据转josnStr

使用场景： 批量删除
   
    let dic1: Dictionary<String,Int> = ["user_id":5, "org_id":12,"class_id": 1]
    
    let dic2:Dictionary<String,Int>=["user_id":5, "org_id":12,"class_id": 1]
    
    let dic3:Dictionary<String,Int>=["user_id":5, "org_id":12,"class_id": 1]
    
    let arr = [dic1,dic2,dic3]
    
    let dic4:Dictionary<String,[Dictionary<String, Int>]>=["lists":arr]
    
    let data = try? JSONSerialization.data(withJSONObject: dic4, options: JSONSerialization.WritingOptions.prettyPrinted)
    let strJson = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
    
    print("strJson===\(String(describing: strJson))")

然后 当参数传给后台