SwiftUI-API取得

例、OpenWeather API
1. JSONを受ける構造体を用意する
2. デコードの例
APIリクエスト時のトークン取得方法(必要ある時)
APIリクエスト時のトークン付与方法(必要ある時)

例、OpenWeather API

JSONを受ける構造体を用意する

Codableを継承させた構造体を用意する。
・変数名はJSONのキーと文字列を合わせる。
・型も受け取れるように合わせる
・階層化している場合は同じく構造体を階層化させて合わせる。
・リストView等で使う場合は Identifiable も継承させる。
→その場合は var id: UUID { UUID() } 等を一番上位の構造体で宣言しておく。

送られてくるJSON

'{"coord":{"lon":141.6809,"lat":45.4176},"weather":[{"id":803,"main":"Clouds","description":"broken clouds","icon":"04d"}],"base":"stations","main":{"temp":290.44,"feels_like":290.29,"temp_min":290.44,"temp_max":290.44,"pressure":1006,"humidity":79,"sea_level":1006,"grnd_level":1004},"visibility":10000,"wind":{"speed":9.71,"deg":23,"gust":10.7},"clouds":{"all":73},"dt":1757809226,"sys":{"country":"JP","sunrise":1757794208,"sunset":1757839685},"timezone":32400,"id":2127515,"name":"Wakkanai","cod":200}'

'{"coord":{"lon":141.6809,"lat":45.4176},"weather":[{"id":803,"main":"Clouds","description":"broken clouds","icon":"04d"}],"base":"stations","main":{"temp":290.44,"feels_like":290.29,"temp_min":290.44,"temp_max":290.44,"pressure":1006,"humidity":79,"sea_level":1006,"grnd_level":1004},"visibility":10000,"wind":{"speed":9.71,"deg":23,"gust":10.7},"clouds":{"all":73},"dt":1757809226,"sys":{"country":"JP","sunrise":1757794208,"sunset":1757839685},"timezone":32400,"id":2127515,"name":"Wakkanai","cod":200}'

Swift側で用意する構造体

import Foundation

struct WeatherResponse: Codable {
    let coord: Coord
    let weather: [Weather]
    let base: String
    let main: Main
    let visibility: Int
    let wind: Wind
    let clouds: Clouds
    let dt: Int
    let sys: Sys
    let timezone: Int
    let id: Int
    let name: String
    let cod: Int
}

struct Coord: Codable {
    let lon: Double
    let lat: Double
}

struct Weather: Codable {
    let id: Int
    let main: String
    let description: String
    let icon: String
}

struct Main: Codable {
    let temp: Double
    let feels_like: Double
    let temp_min: Double
    let temp_max: Double
    let pressure: Int
    let humidity: Int
    let sea_level: Int?
    let grnd_level: Int?
}

struct Wind: Codable {
    let speed: Double
    let deg: Int
    let gust: Double?
}

struct Clouds: Codable {
    let all: Int
}

struct Sys: Codable {
    let country: String
    let sunrise: Int
    let sunset: Int
}

import Foundation

struct WeatherResponse: Codable {

let coord: Coord

let weather: [Weather]

let base: String

let main: Main

let visibility: Int

let wind: Wind

let clouds: Clouds

let dt: Int

let sys: Sys

let timezone: Int

let id: Int

let name: String

let cod: Int

}

struct Coord: Codable {

let lon: Double

let lat: Double

}

struct Weather: Codable {

let id: Int

let main: String

let description: String

let icon: String

}

struct Main: Codable {

let temp: Double

let feels_like: Double

let temp_min: Double

let temp_max: Double

let pressure: Int

let humidity: Int

let sea_level: Int?

let grnd_level: Int?

}

struct Wind: Codable {

let speed: Double

let deg: Int

let gust: Double?

}

struct Clouds: Codable {

let all: Int

}

struct Sys: Codable {

let country: String

let sunrise: Int

let sunset: Int

}

デコードの例

JSONとキーの文字列、構造が合っていないと失敗します。
受け取る個数は合っていなくても問題なく受け取れます、例API側の項目が５つ、アプリ側の項目が３つでもちゃんとデコードに成功します。
受け取りたいデータだけ宣言すればOK。
コードのURLは一度違うサーバーを経由している想定です。

import Foundation

func fetchWeather() {
    guard let url = URL(string: "https://yourdomain.com/api-proxy.php?endpoint=weather?q=Wakkanai&units=metric") else { return }

    URLSession.shared.dataTask(with: url) { data, response, error in
        if let data = data {
            do {
                let weather = try JSONDecoder().decode(WeatherResponse.self, from: data)
                print("都市名: \(weather.name)")
                print("気温: \(weather.main.temp)")
                print("天気: \(weather.weather.first?.description ?? "")")
            } catch {
                print("デコード失敗: \(error)")
            }
        }
    }.resume()
}

import Foundation

func fetchWeather() {

guard let url = URL(string: "https://yourdomain.com/api-proxy.php?endpoint=weather?q=Wakkanai&units=metric") else { return }

URLSession.shared.dataTask(with: url) { data, response, error in

if let data = data {

do {

let weather = try JSONDecoder().decode(WeatherResponse.self, from: data)

print("都市名: \(weather.name)")

print("気温: \(weather.main.temp)")

print("天気: \(weather.weather.first?.description ?? "")")

} catch {

print("デコード失敗: \(error)")

}

}.resume()

}

APIリクエスト時のトークン取得方法(必要ある時)

func fetchToken() async throws -> String {
    let url = URL(string: "https://example.com/wp-json/tsuriba/v1/get-token")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    request.httpBody = " キー ".data(using: .utf8) //JWTのトークンをもらう時のキーを入れる
    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")

    let (data, _) = try await URLSession.shared.data(for: request)
    let result = try JSONDecoder().decode(TokenResponse.self, from: data)
    return result.token
}

struct TokenResponse: Codable {
    let token: String
    let expires_in: Int
}

func fetchToken() async throws -> String {

let url = URL(string: "https://example.com/wp-json/tsuriba/v1/get-token")!

var request = URLRequest(url: url)

request.httpMethod = "POST"

request.httpBody = " キー ".data(using: .utf8) //JWTのトークンをもらう時のキーを入れる

request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")

let (data, _) = try await URLSession.shared.data(for: request)

let result = try JSONDecoder().decode(TokenResponse.self, from: data)

return result.token

}

struct TokenResponse: Codable {

let token: String

let expires_in: Int

}

取得した token を UserDefaultsやKeychainに保存しておき、
その後のAPIリクエストでは Authorization: Bearer <token> を付与してアクセスします。

APIリクエスト時のトークン付与方法(必要ある時)

func fetchWeather(token: String) async throws -> WeatherResponse {
    let url = URL(string: "https://example.com/wp-json/tsuriba/v1/weather")!
    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    // Authorization ヘッダに Bearer トークンを付与
    request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization") //ここ

    let (data, response) = try await URLSession.shared.data(for: request)

    guard let httpResponse = response as? HTTPURLResponse,
          httpResponse.statusCode == 200 else {
        throw URLError(.badServerResponse)
    }

    return try JSONDecoder().decode(WeatherResponse.self, from: data)
}

struct WeatherResponse: Codable {
    let temp: Double
    let wind: String
    let condition: String
}

func fetchWeather(token: String) async throws -> WeatherResponse {

let url = URL(string: "https://example.com/wp-json/tsuriba/v1/weather")!

var request = URLRequest(url: url)

request.httpMethod = "GET"

// Authorization ヘッダに Bearer トークンを付与

request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization") //ここ

let (data, response) = try await URLSession.shared.data(for: request)

guard let httpResponse = response as? HTTPURLResponse,

httpResponse.statusCode == 200 else {

throw URLError(.badServerResponse)

}

return try JSONDecoder().decode(WeatherResponse.self, from: data)

}

struct WeatherResponse: Codable {

let temp: Double

let wind: String

let condition: String

}