SwiftUI 从 api.city.bik 获取 JSON API 数据

问题描述

我在尝试获取此数据时遇到问题。听说有窍门。任何人都可以创建一个简单的调用来查看来自这个 api 的数据吗？真的会很感激。试了一个星期。我一辈子都无法让这个简单的 api 调用起作用。

http://api.citybik.es/v2/networks

Model.swift

library(shiny)
library(shinyWidgets)
library(shinyjs)

jsCode <- 'shinyjs.winprint = function(){
window.print();
}'

ui <- fluidPage(
  fluidPage(title = "Repro"),tags$head(
    tags$style(
      HTML(".shiny-notification {
       position:fixed;
       top: calc(50% - 150px);
       left: calc(50% - 150px);
       }
       "
      )
    )
  ),useShinyjs(),extendShinyjs(text = jsCode,functions = c("winprint")),sidebarLayout(
    sidebarPanel(
      textInput("name","Name"),numericInput("Y1","Y1",value = 0,min =0,max = 200),actionButton("print","PRINT")
      
    ),mainPanel(
      tabsetPanel(type = "tabs",tabPanel("Random Var1",tableOutput("x1"))
      )
    )
  )
)

server <- function(input,output,session) {
  
  Var1 <- c(1,2,3,4,5,6,7,8,9,10)
  X1 <- c(0.01,0.1,0.04,0.01,100,0.5)
  Units <- c("a","a","b","c","c")
  table <- data.frame(Var1,X1,Units)
  
  
  Y1 <- reactive({
    get(input$Y1,inherits = FALSE)
  })
  
  
  
  output$x1 <- renderTable({
    transform(table,X2 = input$Y1 * case_when(Var1 %in% c(1,8) ~ 0.01,Var1 == 2 ~ 1,Var1 %in% c(3,6) ~ 0.04,Var1 == 4 ~ 50,Var1 == 5 ~ 2,Var1 == 9 ~ 4,Var1 == 10 ~ 0.5))
    
    
  })

  observeEvent(input$print,{
    js$winprint()
  })
}

# App
shinyApp(ui,server)

Contentview.swift

import Foundation

// MARK: - Welcome
struct Dataset: Codable {
    let networks: [Network]
}

// MARK: - Network
struct Network: Codable {
    let company: [String]
    let href,id: String
    let location: Location
    let name: String
}

// MARK: - Location
struct Location: Codable {
    let city,country: String
    let latitude,longitude: Double
}

解决方法

从“https://api.citybik.es/v2/networks”复制整个json 进入“https://app.quicktype.io/”并从中获取（正确的）swift数据结构。 将“欢迎”重命名为“响应”并在您的代码中使用它。

使用：“https://api.citybik.es/v2/networks”注意https。

编辑：在您的代码中：

struct ContentView: View {
    @State var networks = [Network]()
    
    var body: some View {
        List(networks,id: \.id) { network in
            VStack {
                Text(network.name)
                Text(network.location.city)
            }
        }.onAppear(perform: loadData)
    }
    
    func loadData() {
        guard let url = URL(string: "https://api.citybik.es/v2/networks") else {
            print("Your API end point is Invalid")
            return
        }
        let request = URLRequest(url: url)
        URLSession.shared.dataTask(with: request) { data,response,error in
            if let data = data {
                if let response = try? JSONDecoder().decode(Response.self,from: data) {
                    DispatchQueue.main.async {
                        self.networks = response.networks
                    }
                    return
                }
            }
        }.resume()
    }
} 

一旦你有了所有的数据结构， 如果你在 ios 15 或 macos 12 上使用 Swift 5.5，你可以使用这样的东西：

struct ContentView: View {
    @State var networks = [Network]()
    
    var body: some View {
        List(networks,id: \.id) { network in
            VStack {
                Text(network.name)
                Text(network.location.city)
            }
        }
        .task {
            let response: Response? = await fetchNetworks()
            if let resp = response {
                networks = resp.networks
            }
        }
    }
    
    func fetchNetworks<T: Decodable>() async -> T? {
        let url = URL(string: "https://api.citybik.es/v2/networks")!
        let request = URLRequest(url: url)
        do {
            let (data,response) = try await URLSession.shared.data(for: request)
            guard let httpResponse = response as? HTTPURLResponse,httpResponse.statusCode == 200 else {
                // throw URLError(.badServerResponse)   //  todo
                print(URLError(.badServerResponse))
                return nil
            }
            let results = try JSONDecoder().decode(T.self,from: data)
            return results
        }
        catch {
            return nil
        }
    }
}