ios - 如何在 Swift3 iOS 中根据键值按升序获取数组

Question

我正在 Swift3 中创建一个数据库应用程序，我必须在其中显示来自 JSON 的 UITableView 中的数据。下面是我的 JSON :

{
    "Success": 1,
    "data": [{
        "Session_Details": [{
                "Start_Time": "08:00",
                "End_Time": "10:00",
                "Tag_Details": [{
                    "Tag_Id": 1,
                    "Tag_Name": "Test 1",
                    "Tag_Order": 4
                }]
            },
            {
                "Start_Time": "10:30",
                "End_Time": "12:30",
                "Tag_Details": [{
                    "Tag_Id": 2,
                    "Tag_Name": "Test 2",
                    "Tag_Order": 1
                }]
            },
            {
                "Start_Time": "10:30",
                "End_Time": "12:30",
                "Tag_Details": [{
                    "Tag_Id": 3,
                    "Tag_Name": "Test 3",
                    "Tag_Order": 3
                }]
            },
            {
                "Start_Time": "13:30",
                "End_Time": "15:20",
                "Tag_Details": [{
                    "Tag_Id": 1,
                    "Tag_Name": "Test 1",
                    "Tag_Order": 4
                }]
            }
        ]
    }]
}

我已经解析了 JSON 并获取了所有 JSON 数据。

我的问题是我必须创建一个应该具有唯一值的“Tag_Details”数组，这意味着 Tag_Id 应该是唯一的。此外，我还必须根据 Tag_Order 键以 升序 顺序设置数组。

我正在尝试下面的代码但没有工作:

var sessions : [SessionData]! {
        return AgendaDataManager.sharedInstance.sessionData
}

let sortedResults = session.tagDetails!.sortedArray(using: [NSSortDescriptor(key: "tagOrder", ascending: true)])

let sessionTag = ((session.tagDetails as AnyObject).allObjects as! [TagData])[0]

请给我建议。谢谢。

Answer 1

如果您使用 Swift 3 编写代码并且无法使用 Codable 协议(protocol)

首先，您应该构建您的 json 数据。您可以使用这个助手 quick type这将提供一个很好的起点:

struct Root {
    let success: Bool
    let data: [Datum]
}

struct Datum {
    let sessionDetails: [SessionDetail]
}

struct SessionDetail {
    let startTime: String
    let endTime: String
    let tagDetails: [TagDetail]
}

struct TagDetail {
    let tagId: Int
    let tagName: String
    let tagOrder: Int
}

---

您需要为您的根结构创建一个自定义初始化程序，该初始化程序采用数据参数(JSON 数据):

typealias Dictionary = [String: Any]
typealias Dictionaries = [[String: Any]]

extension Root {
    init?(_ data: Data) {
        let dictionary = (try? JSONSerialization.jsonObject(with: data)) as? Dictionary ?? [:]
        success = dictionary["Success"] as? Bool == true
        guard success else {
            return nil
        }
        self.data = (dictionary["data"] as! Dictionaries).map(Datum.init)
    }
}

---

以及为所有结构采用字典的初始化器。

extension Datum {
    init(dictionary: [String: Any]) {
        sessionDetails = (dictionary["Session_Details"] as! Dictionaries)
            .map(SessionDetail.init)
    }
}

extension SessionDetail {
    init(dictionary: [String: Any]) {
        startTime = dictionary["Start_Time"] as! String
        endTime = dictionary["End_Time"] as! String
        tagDetails = (dictionary["Tag_Details"] as! Dictionaries).map(TagDetail.init)
    }
}

extension TagDetail: CustomStringConvertible {
    init(dictionary: [String: Any]) {
        tagId = dictionary["Tag_Id"] as! Int
        tagName = dictionary["Tag_Name"] as! String
        tagOrder = dictionary["Tag_Order"] as! Int
    }
    var description: String {
        return "TagDetail(Id: \(tagId) - Name: \(tagName) - Order: \(tagOrder))"
    }
}

接下来您需要使 TagDetail 符合 Equatable 和 Comparable:

extension TagDetail: Equatable, Comparable {
    static func == (lhs: TagDetail, rhs: TagDetail) -> Bool {
        return lhs.tagId == rhs.tagId
    }
    static func < (lhs: TagDetail, rhs: TagDetail) -> Bool {
        return lhs.tagOrder < rhs.tagOrder
    }
}

---

完成所有这些步骤后，您可以轻松地过滤和排序对象:

---

let data = Data("""
{
"Success": 1,
"data": [{
"Session_Details": [{
"Start_Time": "08:00",
"End_Time": "10:00",
"Tag_Details": [{
"Tag_Id": 1,
"Tag_Name": "Test 1",
"Tag_Order": 4
}]
},
{
"Start_Time": "10:30",
"End_Time": "12:30",
"Tag_Details": [{
"Tag_Id": 2,
"Tag_Name": "Test 2",
"Tag_Order": 1
}]
},
{
"Start_Time": "10:30",
"End_Time": "12:30",
"Tag_Details": [{
"Tag_Id": 3,
"Tag_Name": "Test 3",
"Tag_Order": 3
}]
},
{
"Start_Time": "13:30",
"End_Time": "15:20",
"Tag_Details": [{
"Tag_Id": 1,
"Tag_Name": "Test 1",
"Tag_Order": 4
}]
}
]
}]
}
""".utf8)

---

if let root = Root(data), root.success,
    let sessionDetails = root.data.first?.sessionDetails {
    for detail in sessionDetails {
        print(detail)
    }
    let allTagDetails = sessionDetails.flatMap{$0.tagDetails}
    let tagDetailsSorted = allTagDetails.sorted()
    print("\n\n\n")
    var set = Set<Int>()
    let tagDetailsSortedSet = tagDetailsSorted.filter({ set.insert($0.tagId).inserted })
    tagDetailsSortedSet.map{print($0)}
}

这将打印

SessionDetail(startTime: "08:00", endTime: "10:00", tagDetails: [TagDetail(Id: 1 - Name: Test 1 - Order: 4)])

SessionDetail(startTime: "10:30", endTime: "12:30", tagDetails: [TagDetail(Id: 2 - Name: Test 2 - Order: 1)])

SessionDetail(startTime: "10:30", endTime: "12:30", tagDetails: [TagDetail(Id: 3 - Name: Test 3 - Order: 3)])

SessionDetail(startTime: "13:30", endTime: "15:20", tagDetails: [TagDetail(Id: 1 - Name: Test 1 - Order: 4)])

和

TagDetail(Id: 2 - Name: Test 2 - Order: 1)

TagDetail(Id: 3 - Name: Test 3 - Order: 3)

TagDetail(Id: 1 - Name: Test 1 - Order: 4)