swift4 – Swift 4使用Codable解码json

发布时间：2020-12-14 05:38:27 所属栏目：百科来源：网络整理

导读：有人能告诉我我做错了什么吗？我已经看过这里的所有问题,就像从这里 How to decode a nested JSON struct with Swift Decodable protocol?一样,我发现了一个看起来正是我需要的东西 Swift 4 Codable decoding json. {"success": true,"message": "got the lo

有人能告诉我我做错了什么吗？我已经看过这里的所有问题,就像从这里 How to decode a nested JSON struct with Swift Decodable protocol?一样,我发现了一个看起来正是我需要的东西 Swift 4 Codable decoding json.

{
"success": true,"message": "got the locations!","data": {
    "LocationList": [
        {
            "LocID": 1,"LocName": "Downtown"
        },{
            "LocID": 2,"LocName": "Uptown"
        },{
            "LocID": 3,"LocName": "Midtown"
        }
     ]
  }
}

struct Location: Codable {
    var data: [LocationList]
}

struct LocationList: Codable {
    var LocID: Int!
    var LocName: String!
}

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    let url = URL(string: "/getlocationlist")

    let task = URLSession.shared.dataTask(with: url!) { data,response,error in
        guard error == nil else {
            print(error!)
            return
        }
        guard let data = data else {
            print("Data is empty")
            return
        }

        do {
            let locList = try JSONDecoder().decode(Location.self,from: data)
            print(locList)
        } catch let error {
            print(error)
        }
    }

    task.resume()
}

我得到的错误是：

typeMismatch(Swift.Array,Swift.DecodingError.Context(codingPath:
[],debugDescription: “Expected to decode Array but found a
dictionary instead.”,underlyingError: nil))

检查JSON文本的概述结构：

{
    "success": true,"data": {
      ...
    }
}

“data”的值是JSON对象{…},它不是数组.
和对象的结构：

{
    "LocationList": [
      ...
    ]
}

该对象有一个单独的条目“LocationList”：[…],它的值是一个数组[…].

您可能还需要一个结构：

struct Location: Codable {
    var data: LocationData
}

struct LocationData: Codable {
    var LocationList: [LocationItem]
}

struct LocationItem: Codable {
    var LocID: Int!
    var LocName: String!
}

用于检测…

var jsonText = """
{
    "success": true,"data": {
        "LocationList": [
            {
                "LocID": 1,"LocName": "Downtown"
            },{
                "LocID": 2,"LocName": "Uptown"
            },{
                "LocID": 3,"LocName": "Midtown"
            }
        ]
    }
}
"""

let data = jsonText.data(using: .utf8)!
do {
    let locList = try JSONDecoder().decode(Location.self,from: data)
    print(locList)
} catch let error {
    print(error)
}

（编辑：李大同）

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