使用 Alamofire 和使用 Swift 5 时无法获取键的值

Question

以下是我使用 Alamofire 调用 GET api 以获取火车详细信息的代码：

var url:String!
    url = "https://api.railwayapi.com/v2/name-number/train/bhopal/apikey/iixp5yxd/"
    Alamofire.request(url, method: .get, encoding: JSONEncoding.default)
        .responseJSON { response in

            switch response.result {

            case .success(let json):
                print(json)
                if let json = response.result.value as? [String:Any] {
                    print(json["train"]!)
                    if let nestedDictionary1 = json["train"] as? [String: AnyObject] {
                        // access individual value in dictionary

                        if let views = nestedDictionary1["number"] as? String {
                             print(views)
                        }

                        if let classes = nestedDictionary1["classes"] as? [String: AnyObject] {
                             print(classes)
                        }
                    }
                }
                DispatchQueue.main.async {

                 // handle your code

               }
            case .failure(let error):
                print(error)
            }
    }

在 print(json) 行，我得到以下 JSON 响应：

{
debit = 1;
"response_code" = 200;
train =     {
    classes =         (
                    {
            available = N;
            code = 2S;
            name = "SECOND SEATING";
        },
                    {
            available = N;
            code = FC;
            name = "FIRST CLASS";
        },
                    {
            available = Y;
            code = 2A;
            name = "SECOND AC";
        },
                    {
            available = N;
            code = 3E;
            name = "3rd AC ECONOMY";
        },
                    {
            available = Y;
            code = SL;
            name = "SLEEPER CLASS";
        },
                    {
            available = N;
            code = CC;
            name = "AC CHAIR CAR";
        },
                    {
            available = Y;
            code = 3A;
            name = "THIRD AC";
        },
                    {
            available = Y;
            code = 1A;
            name = "FIRST AC";
        }
    );
    days =         (
                    {
            code = MON;
            runs = Y;
        },
                    {
            code = TUE;
            runs = Y;
        },
                    {
            code = WED;
            runs = Y;
        },
                    {
            code = THU;
            runs = Y;
        },
                    {
            code = FRI;
            runs = Y;
        },
                    {
            code = SAT;
            runs = Y;
        },
                    {
            code = SUN;
            runs = Y;
        }
    );
    name = "SHAN-E- BHOPAL EXP";
    number = 12156;
};

}

如何提取键 "Classes" 的值和 "Classes" 的相应键。我在上面的代码中使用了它，但不幸的是它不起作用：

if let classes = nestedDictionary1["classes"] as? [String: AnyObject] {
                             print(classes)
                        }

由于我是 Alamofire 的新手，请告诉我哪里出错了以及如何解决这个问题？

Answer 1

请阅读输出。 JSON 只有两种集合类型，数组 []（在输出 () 中）和字典 {}.

所以键 classes 的值显然是一个数组 ([[String:Any]]) 并且 JSON 未指定的值总是 Any，永远不会 AnyObject。

并且请使用更具描述性的变量名。

if let json = response.result.value as? [String:Any] {

    if let train = json["train"] as? [String: Any] {
        print(train)
        // access individual value in dictionary

        if let number = train["number"] as? String { // more likely `Int`
             print(number)
        }

        if let classes = train["classes"] as? [[String: Any]] {
             for aClass in classes {
                 let name = aClass["name"] as! String
                 let available = aClass["available"] as! String
                 print(name, available)

             }
        }
    }
}

尽管如此，还是考虑使用 Codable 协议。更方便更高效

使用 Alamofire 和使用 Swift 5 时无法获取键的值

Unable to get the value of a key while using Alamofire and using Swift 5

ios

swift

alamofire

swift5

xcode11