如何訪問JSON陣列中的單個值|迅速

本質上，我在加載 tableview 控制器時執行以下函式。使用 JSON 回應值之一，我想創建一個條件 - 如何在以下pawprint位置列印值myid == 3：

我試圖DispatchQueue.main.async在同一個函式中訪問它，但我很困惑如何參考它？例如我不能做 myData.pawprint - 因為它是一個 JSON 陣列。

private func fetchJSON() {
        guard let url = URL(string: "test.com")
        else { return }
        
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.httpBody = "mykey=\(keyValue)".data(using: .utf8)
        
        URLSession.shared.dataTask(with: request) { [self] data, _, error in
            guard let data = data else { return }
            
            do {
                
                let decoder = JSONDecoder()
                self.structure.sort { $0.thisdate > $1. thisdate }
                let res = try decoder.decode([thisStructure].self, from: data)
                let grouped = Dictionary(grouping: res, by: { $0. thisdate })
                _ = grouped.keys.sorted()
                sections = grouped.map { thisSections(date: $0.key, items: $0.value) }
                .sorted { $0.date > $1.date }
                print(sections.map(\.date))
                
                sections.map.
                let myData = try JSONDecoder().decode(thisStructure.self, from: data)
                
                DispatchQueue.main.async {
                    self.tableView.reloadData()
                    print("TableView Loaded")
                    
                }
            }
            catch {
                print(error)
            }
        }.resume()
        
    }

struct thisSections {
    let date : String
    var items : [thisStructure]
}


struct thisStructure: Decodable {
    let myid: Int
    let pawprint: String
    let activationid: Int
    let stopid: Int
}

JSON 回應示例：

[
  {
    "myid": 3,
    "pawprint": "Print Me",
    "activationid": 2,
    "stopid": 1
  }
]

uj5u.com熱心網友回復：

MyData.forEach {
    item in 
   if item.myid == 3{
     prin(\(item.pawprint))
   }
}

你在找這個嗎？

uj5u.com熱心網友回復：

您可以嘗試這種方法來選擇，然后列印thisStructure pawprint您想要的具體內容：

private func fetchJSON() {
        guard let url = URL(string: "test.com")
        else { return }

        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.httpBody = "mykey=\(keyValue)".data(using: .utf8)

        URLSession.shared.dataTask(with: request) { [self] data, _, error in
            guard let data = data else { return }

            do {
                let decoder = JSONDecoder()
                self.structure.sort { $0.thisdate > $1. thisdate }
                let res = try decoder.decode([thisStructure].self, from: data)
                let grouped = Dictionary(grouping: res, by: { $0. thisdate })
                _ = grouped.keys.sorted()
                sections = grouped.map { thisSections(date: $0.key, items: $0.value) }
                .sorted { $0.date > $1.date }
                print(sections.map(\.date))

                // --- here res is an array of `thisStructure`
                if let selectedOne = res.first(where: {$0.myid == 3}) {
                    print(selectedOne.pawprint)
                }

                // do not try to decode this from the data
                //  let myData = try JSONDecoder().decode(thisStructure.self, from: data)

                DispatchQueue.main.async {
                    self.tableView.reloadData()
                    print("TableView Loaded")
                }
            }
            catch {
                print(error)
            }
        }.resume()

    }

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