Question

如果标题不清楚，我道歉。我不太确定NSDictionary和JSON究竟是如何工作的。

我正在尝试使用Swift创建一个简单的应用程序，该应用程序从.JSON文件获取值，并将它们打印到控制台。这是我的JSON文件：

{

"students": [
    {
        "name": "Stew Dent",
        "age": "10",
        "year": 6,
        "grades": [
            {
                "english": "a-plus",
                "math": "b-plus"
            },
            {
                "english": "a",
                "math": "a-minus"
            }
        ]

    },

    {
        "name": "Mary Brown",
        "age": "14",
        "year": 10,
        "grades": [
            {
                "english": "a-plus",
                "math": "a-plus"
            },
            {
                "english": "a-plus",
                "math": "a"
            }
        ]

    }
]

}

目前，我能够检索除＆＃34; grade＆＃34;中的值以外的所有值。这是我的Swift代码：

if let path = Bundle.main.path(forResource: "school", ofType: "json")
    {
        do {
            // Retrieve data from JSON file
            let jsonData = try NSData(contentsOfFile: path, options: .mappedIfSafe)

            // Convert data into NSDictionary
            let jsonResult = try JSONSerialization.jsonObject(with: jsonData as Data, options: JSONSerialization.ReadingOptions.mutableContainers) as? NSDictionary



            if let students : [NSDictionary] = jsonResult?["students"] as? [NSDictionary]
            {
                if let grades : [NSDictionary] = students["grades"] as? [NSDictionary]
                {
                    for grade: NSDictionary in grades
                    {
                        for (subject, gradevalue) in grade
                        {
                            print ("\(subject): \(gradevalue)")
                        }

                    }
                }



            }



        } catch
        {

        }


    }

如果我没有错，那么＆＃34;成绩＆＃34;是一个字典里面的学生＆＃34;字典。但是，它无法运行上面的代码。在＆＃34;如果让等级......＆＃34;行，它给出错误信息：＆＃34;不能下标类型的值＆＃39; [NSDictionary]＆＃39;索引类型为＆＃39; String＆＃39;。

那么我做错了什么？有没有办法检索这些值？我错过了什么吗？任何帮助将不胜感激。谢谢:)）

Answer 1

您应该使用Swift原生类型Data代替NSData和词典[String:Any]而不是NSDictionary。你也忘了遍历每个学生。试试这样：

do {
    if let dict = try JSONSerialization.jsonObject(with: jsonData) as? [String: Any] {
        print(dict)
        if let students = dict["students"] as? [[String: Any]] {
            print(students)
            for student in students {
                print(student["name"] ?? "")
                if let grades = student["grades"] as?  [[String: Any]] {
                    for grade in grades {
                        for (subject, gradevalue) in grade {
                            print ("student:",student["name"] ?? "", "subject:", subject, "grade:", gradevalue)
                        }
                    }
                }
            }
        }
    }
} catch {
    print(error)
}

Answer 2

尝试使用此代码，这应该可以查看您要执行的操作

            if let path = Bundle.main.path(forResource: "student", ofType: "json")
    {
        do {
            // Retrieve data from JSON file
            let jsonData = try NSData(contentsOfFile: path, options: .mappedIfSafe)

            // Convert data into NSDictionary
            let jsonResult = try JSONSerialization.jsonObject(with: jsonData as Data, options: JSONSerialization.ReadingOptions.mutableContainers) as? NSDictionary



            if let students = jsonResult?["students"] as? [NSDictionary]
            {
                for student in students
                {
                    for grades in student["grades"] as! [[String:String]]{
                        for eachGrade in grades{
                            print("\(eachGrade.key) : \(eachGrade.value)")
                        }

                    }
                }
            }
        }
        catch
        {

        }

}

如何在NSDictionary中获取嵌套在字典中的值？

2 个答案: