问题描述
我试图连接我的API数据以在单元格中查看它，但看来我听不到我的回应，而且总是== nil 下面的代码描述了Country.SWIFT // Model.SWIFT // Response.SWIFT，它们显示了如何使用Codable获得JSON响应 and CountryCell.SWIFT显示了我如何使用它来调用API API图片的链接：https://i.stack.imgur.com/jyoON.jpg
Country.SWIFT
struct Country: Decodable {
var CountryName = ""
var CountryImage = ""
var objectId = ""
// MARK: - Coding Keys
enum CodingKeys: String,CodingKey {
case CountryName = "CountryName"
case CountryImage = "CountryImage"
case objectId = "objectId"
}
//MARK: - Json Decoder
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
// Parsing our attributes
self.CountryName = try container.decode(String.self,forKey: .CountryName)
self.CountryImage = try container.decode(String.self,forKey: .CountryImage)
self.objectId = try container.decode(String.self,forKey: .objectId)
}
}]
Model.SWIFT
protocol ModelDelegate {
func countriesFetched (_ countries: [Country])
}
class Model {
//MARK: - Vars
var delegate: ModelDelegate?
// MARK: - Get Countries
func getCountries () {
// URL Object
let url = URL(string: Constants.API_URL)
guard url != nil else {return}
// URL Session object
let session = URLSession.shared
//Data Task from URLSession object
let dataTask = session.dataTask(with: url!) { (data,response,error) in
if error != nil || data == nil {
print(error!.localizedDescription)
return
}
print(data!)
do {
let decoder = JSONDecoder()
let response = try decoder.decode(Response.self,from: data!)
if response.items != nil {
dispatchQueue.main.async {
self.delegate?.countriesFetched(response.items!)
}
}
}
catch {
}
}
// start data task
dataTask.resume()
}
}
Response.SWIFT
struct Response: Decodable {
var items: [Country]? = []
init(from decoder: Decoder) throws {
var itemsContrainer = try decoder.unkeyedContainer()
self.items = try itemsContrainer.decode([Country].self)
}
}
CountryCell.SWIFT
class CountryCell: UICollectionViewCell {
//MARK: - Vars
var country: Country?
//MARK: - Outlets
@IBOutlet weak var imageViewCountryOutlet: UIImageView!
@IBOutlet weak var lblCountryNameOutlet: UILabel!
//MARK: - Creating Cell
func generateCell (_ myCountry: Country) {
self.country = myCountry
guard self.country != nil else { return }
lblCountryNameOutlet.text = country!.CountryName
guard self.country!.CountryImage != "" else {return}
let url = URL(string: self.country!.CountryImage)
guard url != nil else {return}
let session = URLSession.shared
let dataTask = session.dataTask(with: url!) { (data,error) in
if error == nil || data != nil {
if url!.absoluteString != self.country!.CountryImage {
return
}
let image = UIImage(data: data!)
dispatchQueue.main.async {
self.imageViewCountryOutlet.image = image
}
}
}
dataTask.resume()
}
}
解决方法
不需要包装Response类型，直接解码国家列表：
let decoder = JSONDecoder()
let items = try decoder.decode([Country].self,from: data!)
在您的代码中，当您在 Response 中请求 unkeyedContainer 时，预期的 JSON 结构将需要额外的嵌套数组。
检查 catch 块中的解码错误
do {
...
}
catch {
print(error)
}
我知道这听起来有点荒谬，但就我而言，通过使用 class 而不是 struct 并使用 public var 声明所有属性对我有用。