动态更改基础货币

Question

我有一个货币API，它返回一个包含奇怪排列的JSON对象：基本货币用作标签。典型的货币API具有诸如"；"碱"日期""成功"；，以及"；费率"；，但是这个API没有这些。

{
"usd": {
"aed": 4.420217,
"afn": 93.3213,
"all": 123.104693,
"amd": 628.026474,
"ang": 2.159569,
"aoa": 791.552347,
"ars": 111.887966,
"aud": 1.558363,
"awg": 2.164862,
"azn": 2.045728,
"bam": 1.9541,
"bbd": 2.429065,
"bch": 0.001278
}
}

"；美元；顶部的(美元(被称为基础货币或本国货币。此时存储结构和状态参数被硬编码为"0"；美元；这防止使用与其他基础货币的汇率。API汇率对美元基础货币非常有效。

我需要帮助修改东西，这样我就可以下载不同基础货币的汇率。例如，我可以在存储模型和状态参数中使用字符串变量吗？任何启示都将不胜感激。

struct RateResult: Codable {
let usd: [String: Double]
}    
@State private var  results = RateResult(usd: [:])

struct ContentView: View {
var body: some View {
}
func UpdateRates() {
let baseUrl = "https://cdn.jsdelivr.net/gh/fawazahmed0/currency-api@1/latest/currencies/"
let baseCur = baseCurrency.baseCur.baseS   // usd
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 {
if let decodedResponse = try? JSONDecoder().decode(RateResult.self, from: data) {

// we have good data – go back to the main thread
DispatchQueue.main.async {

// update our UI
self.results = decodedResponse

// save off currency exchange rates

}
// everything is good, so we can exit
return
}
}
// if we're still here it means there was a problem
print("Currency Fetch Failed: (error?.localizedDescription ?? "Unknown error")")
}.resume()
}
}

Answer 1

import SwiftUI
//You can't use the standard Codable for this. You have to make your own.
class BaseCurrency: Codable {
let id = UUID()
var baseCurrencies: [String : [String: Double]] = [:]
required public init(from decoder: Decoder) throws {
do{
print(#function)
let baseContainer = try decoder.singleValueContainer()
let base = try baseContainer.decode([String : [String: Double]].self)
for key in base.keys{
baseCurrencies[key] = base[key]
}
}catch{
print(error)
throw error
}
}
//@State should never be used outside a struct that is a View
}
struct CurrencyView: View {
@StateObject var vm: CurrencyViewModel = CurrencyViewModel()

var body: some View {
VStack{
List{
if vm.results != nil{
ForEach(vm.results!.baseCurrencies.sorted{$0.key < $1.key}, id: .key) { key, baseCurrency in
DisclosureGroup(key){
ForEach(baseCurrency.sorted{$0.key < $1.key}, id: .key) { key, rate in
HStack{
Text(key)
Text(rate.description)
}
}
}
}
}else{
Text("waiting...")
}
}
//To select another rate to go fetch
RatesPickerView().environmentObject(vm)
}.onAppear(){
vm.UpdateRates()
}
}
}
struct RatesPickerView: View {
@EnvironmentObject var vm: CurrencyViewModel
var body: some View {
if vm.results != nil{
//You can probaly populate this picker with the keys in
// baseCurrency.baseCur.baseS
Picker("rates", selection: $vm.selectedBaseCurrency){
ForEach((vm.results!.baseCurrencies.first?.value.sorted{$0.key < $1.key})!, id: .key) { key, rate in
Text(key).tag(key)
}
}
}else{
Text("waiting...")
}
}
}
class CurrencyViewModel: ObservableObject{

@Published var results: BaseCurrency?
@Published var selectedBaseCurrency: String = "usd"{
didSet{
UpdateRates()
}
}
init() {
//If you can .onAppear you don't need it here
//UpdateRates()
}
func UpdateRates() {
print(#function)
let baseUrl = "https://cdn.jsdelivr.net/gh/fawazahmed0/currency-api@1/latest/currencies/"
let baseCur = selectedBaseCurrency   // usd
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 decodedResponse = try JSONDecoder().decode(BaseCurrency.self, from: data)

DispatchQueue.main.async {

if self.results == nil{
//Assign a new base currency
self.results = decodedResponse
}else{ //merge the existing with the new result
for base in decodedResponse.baseCurrencies.keys{
self.results?.baseCurrencies[base] = decodedResponse.baseCurrencies[base]
}
}
//update the UI
self.objectWillChange.send()
}

}catch{
//Error thrown by a try
print(error)//much more informative than error?.localizedDescription
}
}
if error != nil{
//data task error
print(error!)
}
}.resume()
}
}
struct CurrencyView_Previews: PreviewProvider {
static var previews: some View {
CurrencyView()
}
}