Question

我想像这样过滤数据集：

例如，这是一些假数据集：

[
    {
      "name": "Sakura",
      "hasChildren": false,
      "livesInCity": true,
      "pets": [
          { 
              "cats": ["Luna", "Milk"],
              "type": "tabby"
          }
       ]
    },
    {
      "name": "Linn",
      "hasChildren": false,
      "livesInCity": true,
      "pets": [
          { 
              "cats": ["Luna"],
              "type": "tabby"
          }
       ]
    },
    {
      "name": "Donna",
      "hasChildren": false,
      "livesInCity": false,
      "pets": [
          { 
              "cats": ["Luna", "Milk"],
              "type": "tabby"
          }
       ]
    },
    {
      "name": "Tia",
      "hasChildren": false,
      "livesInCity": false,
      "pets": [
          { 
              "cats": ["Luna", "Milk"],
              "type": "tuxedo"
          }
       ]
    },
    {
      "name": "Dora",
      "hasChildren": false,
      "livesInCity": true,
      "pets": [
          { 
              "cats": ["Artemis", "Milk"],
              "type": "tuxedo"
          }
       ]
    }
]

我想过滤出所有包含"livesInCity": false的内容：

[
    {
      "name": "Sakura",
      "hasChildren": false,
      "livesInCity": true,
      "pets": [
          { 
              "cats": ["Luna", "Milk"],
              "type": "tabby"
          }
       ]
    },
    {
      "name": "Linn",
      "hasChildren": false,
      "livesInCity": true,
      "pets": [
          { 
              "cats": ["Luna"],
              "type": "tabby"
          }
       ]
    },
    {
      "name": "Dora",
      "hasChildren": false,
      "livesInCity": true,
      "pets": [
          { 
              "cats": ["Artemis", "Milk"],
              "type": "tuxedo"
          }
       ]
    }
]

我该怎么做？这可能吗？

我相信在python中是这样的，但是我不知道如何开始使用Swift：

people = [person for person in people if person.livesInCity == True]

此外，如何过滤上面的数据集看起来像这样-我想按名称类型进行分类。

{
    "tabby": ["Sakura", "Linn"],
    "tuxedo": ["Dora"],
}

任何帮助将不胜感激！

Answer 1

正如评论中已经提到的那样，您不能直接在Swift中处理JSON对象。他们需要先进行转换。

您可以将JSON解析为Swift对象，然后执行过滤，分组等。

struct Person: Codable {
    let name: String
    let hasChildren: Bool
    let livesInCity: Bool
    let pets: [Pet]
}

struct Pet: Codable {
    let cats: [String]
    let type: String
}

let jsonStr = "[{"name": "Sakura", ..." // your JSON string
let jsonData = jsonStr.data(using: .utf8)!
let parsedObjects = try! JSONDecoder().decode([Person].self, from: data)

然后，您可以过滤您的parsedObjects：

let filteredObjects = parsedObjects.filter({ person in person.livesInCity == true })

或更短版本（ swiftier ）：

let filteredObjects = parsedObjects.filter { $0.livesInCity }

您也可以尝试按宠物类型分组：

var groupedDict = [String:[String]]()
filteredObjects.forEach{ person in
    person.pets.forEach { pet in
        if let _ = groupedDict[pet.type] {
            groupedDict[pet.type]!.append(person.name)
        } else {
            groupedDict[pet.type] = [person.name]
        }
    }
}

print(groupedDict)
//prints ["tabby": ["Sakura", "Linn"], "tuxedo": ["Dora"]]

如果您想随时将对象转换回JSON，可以使用：

let dictData = try! JSONEncoder().encode(groupedDict)
let dictStr = String(data: dictData, encoding: .utf8)!

print(dictStr)
//prints {"tabby":["Sakura","Linn"],"tuxedo":["Dora"]}

注意

为简单起见，在解码/编码对象时，我使用了强制可选展开（!）。您可能需要改用do-try-catch（以捕获错误）。

如何从JSON对象数组中删除具有特定键/值对的所有JSON对象？

1 个答案: