markvanwijnen

private var tokenCredentials: TokenCredentials?

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struct TokenCredentials {
    let accessToken: String
    let accessTokenSecret: String
}

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func oAuthAccessTokenPublisher(temporaryCredentials: TemporaryCredentials, verifier: String) -> AnyPublisher<(TokenCredentials, User), OAuthError> {
    // 1
    let request = (baseURLString: "https://api.twitter.com/oauth/access_token",
                   httpMethod: "POST",
                   consumerKey: ClientCredentials.APIKey,
                   consumerSecret: ClientCredentials.APIKeySecret)
    
    // 2
    guard let baseURL = URL(string: request.baseURLString) else {
        return Fail(error: OAuthError.urlError(URLError(.badURL)))

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private var subscriptions: [String: AnyCancellable] = [:] // 1

func authorize() {
    // 2
    guard !self.authorizationSheetIsPresented else { return }
    self.authorizationSheetIsPresented = true

    // 3
    self.subscriptions["oAuthRequestTokenSubscriber"] =
        self.oAuthRequestTokenPublisher()

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import SwiftUI

struct ContentView: View {
    @EnvironmentObject var twitterAPI: TwitterAPI // 1

    var body: some View {
        VStack {
            if let screenName = twitterAPI.user?.screenName { // 2
                Text("Welcome").font(.largeTitle)
                Text(screenName).font(.largeTitle)

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class TwitterAPI: NSObject, ObservableObject {
    @Published var authorizationSheetIsPresented = false // 1
    @Published var authorizationURL: URL? // 2
    @Published var user: User? // 3
    
    struct User {
        let ID: String
        let screenName: String
    }
    

markvanwijnen

import SwiftUI
import SafariServices

struct SafariView: UIViewControllerRepresentable {
    // 1
    class SafariViewControllerWrapper: UIViewController {
        // 2
        private var safariViewController: SFSafariViewController?
        
        // 3

markvanwijnen

func oAuthRequestTokenPublisher() -> AnyPublisher<TemporaryCredentials, OAuthError> {
    // 1
    let request = (baseURLString: "https://api.twitter.com/oauth/request_token",
                   httpMethod: "POST",
                   consumerKey: ClientCredentials.APIKey,
                   consumerSecret: ClientCredentials.APIKeySecret,
                   callbackURLString: "\(ClientCredentials.CallbackURLScheme)://")

    // 2
    guard let baseURL = URL(string: request.baseURLString) else {

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struct TemporaryCredentials {
    let requestToken: String
    let requestTokenSecret: String
}

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enum OAuthError: Error {
    case unknown
    case urlError(URLError)
    case httpURLResponse(Int)
    case cannotDecodeRawData
    case cannotParseResponse
    case unexpectedResponse
    case failedToConfirmCallback
}