API 数据的初始化和存储错误

Question

我有一个汇率 API 初始化/存储问题。我读取了一些货币汇率，并希望将数据暂时存储在 moneyRates 中，然后将数据作为有序数据移动到 rateArray。我收到错误消息“初始化程序调用中没有完全匹配”。错误发生在以“let result = try JSONSerialization...”开头的行。我还在边栏中看到一条消息（Xcode 灰色！）“/Foundation.Data:29:23：候选人要求类型 'MoneyRates' 和 'UInt8' 等效（要求指定为 'S.Element' == 'UInt8')”。我猜我需要用某种格式信息来初始化 moneyRates。

我想要一些关于 moneyRates 错误的解释以及如何解决它。此时我不关心 rateArray。感谢您的帮助。

struct MoneyRates {
    let date: String
    let base: String
    let rates: [String: Double]
}

class CurrencyRates: ObservableObject{
    
    @Published var moneyRates: [MoneyRates]
    @Published var rateArray = [Double] ()
    
    init() {
        if UserDefaults.standard.array(forKey: "rates") != nil {
            rateArray = UserDefaults.standard.array(forKey: "rates") as! [Double]
            
        } else {
            rateArray = [Double] (repeating: 0.0, count: 170)
            UserDefaults.standard.set(self.rateArray, forKey: "rates")
        }
    }
    
    // retrieve exchange rates for all 150+ countries from internet and save to rateArray
    func updateRates(baseCur: String) {
                 
        let baseUrl = "https://cdn.jsdelivr.net/gh/fawazahmed0/currency-api@1/latest/currencies/"
        let requestType = ".json"
        
        guard let url = URL(string: baseUrl + baseCur + requestType) else {
            print("Invalid URL")
            return
        }
        let request = URLRequest(url: url)
        
        URLSession.shared.dataTask(with: request) { data, response, error in
            
            if let data = data {
                do {
                let result = try JSONSerialization.jsonObject(with: Data(moneyRates)) as! [String:Any] // <-- error is occurring here
                    
                    var keys = Array(arrayLiteral: result.keys)
                    if let dateIndex = keys.firstIndex(of: "date"),
                       let date = result[keys[dateIndex]] as? String, keys.count == 2 {
                        keys.remove(at: dateIndex)
                        let base = keys.first!
                        let rates = MoneyRates(date: date, base: base, rates: result[base] as! [String:Double])
                        print(rates)
                    }
                } catch {
                    print(error)
                }
            }
            
        }.resume()
    }
}

Answer 1

如果您尝试解码从 URLSession 获得的结果，那么您应该从 [=] 传递 data 而不是传递 Data(moneyRates) 进行解码14=] 闭包：

let result = try JSONSerialization.jsonObject(with: data) as! [String:Any]

API 数据的初始化和存储错误

Initialization and Storage Error of API Data

swiftui

ios14