迅捷|發出連續網路請求的最佳方式？

我最近一直在練習 RxSwift，但是在發出網路請求時遇到了問題。

問題是我怎樣才能發出連續的網路請求。

例如，在 Github api 中，我應該使用https://api.github.com/user/starred/{\owner}/{\repository_name}來檢查用戶是否為存盤庫加注星標。

它應該在我收到請求的資料后發送，但我很難實作這一點。

這是我到目前為止所嘗試的：

import RxSwift

// Struct used to encode response
struct RepositoryResponse: Codable  {
    let items: [Item]
    
    enum CodingKeys: String, CodingKey {
        case items
    }
    
    struct Item: Codable {
        let fullName: String
        
        enum CodingKeys: String, CodingKey {
            case fullName = "full_name"
        }
    }
}

// Actual data for further use
struct Repository {
    let item: RepositoryResponse.Item
    
    var fullName: String {
        return item.fullName
    }
    
    var isStarred: Bool
    
    init(_ item: RepositoryData, isStarred: Bool) {
        self.item = item
        self.isStarred = isStarred
    }
}

// Url components
var baseUrl = URLComponents(string: "https://api.github.com/search/repositories")   // base url
let query = URLQueryItem(name: "q", value: "flutter")    // Keyword. flutter for this time.
let sort = URLQueryItem(name: "sort", value: "stars")   // Sort by stars
let order = URLQueryItem(name: "order", value: "desc")  // Desc order
baseUrl?.queryItems = [query, sort, order]


// Observable expected to return Observable<[Repository]>
Observable<URL>.of((baseUrl?.url)!)
    .map { URLRequest(url: $0) }
    .flatMap { request -> Observable<(response: HTTPURLResponse, data: Data)> in
        return URLSession.shared.rx.response(request: request)
    }
    .filter { response, data in
        return 200..<300 ~= response.statusCode
    }
    .map { _, data -> [RepositoryResponse.Item] in
        let decoder = JSONDecoder()
        if let decoded = try? decoder.decode(RepositoryResponse.self, from: data) {
            return decoded.items
        } else {
            print("ERROR: decoding")
            return [RepositoryResponse.Item]()
        }
    }
    .map { items -> [Repository] in
        let repos = items.map { item -> Repository in
            var isStarred: Bool?
            
            /// I want to initialize Repository with isStarred value
            /// What should I do in here?
            
            return Repository(item, isStarred: isStarred)
        }
        
        return repos
    }

我計劃做的是通過 Github 搜索 api 獲取存盤庫，然后檢查用戶是否已為每個存盤庫加注星標。

所以我制作了Repository一個結構，它有兩個變數，每個變數包含存盤庫的名稱和星號狀態。

問題就出現在這里。要初始化存盤庫結構，我應該獲得星號狀態。

我嘗試了一種完成方式，但它似乎在完成回傳值之前回傳。

    private func isRepoStarred(name: String, completion: @escaping (Bool) -> Void) {
        let isStarredCheckerUrl = URL(string: "https://api.github.com/user/starred/\(name)")!
        URLSession.shared.dataTask(with: isStarredCheckerUrl) { _, response, _ in
            guard let response = response as? HTTPURLResponse else {
                return
            }
            
            let code = response.statusCode
            if code == 404 {
                return completion(false)
            } else if code == 204 {
                return completion(true)
            } else {
                return completion(false)
            }
        }
    }

我嘗試過的另一種方法是讓Singleobservable 但不知道如何準確地使用它。

func isRepoStarredObs(name: String) -> Single<Bool> {
        return Single<Bool>.create { observer in
            let isStarredCheckerUrl = URL(string: "https://api.github.com/user/starred/\(name)")!
            let task = URLSession.shared.dataTask(with: isStarredCheckerUrl) { _, response, _ in
                guard let response = response as? HTTPURLResponse else {
                    return
                }
                
                let code = response.statusCode
                if code == 404 {
                    observer(.success(false))
                } else if code == 204 {
                    observer(.success(true))
                } else {
                    observer(.failure(NSError(domain: "Invalid response", code: code)))
                }
            }
            task.resume()
            
            return Disposables.create { task.cancel() }
        }
    }

如果您有任何想法，請告訴我。謝謝。

uj5u.com熱心網友回復：

這將獲得星標狀態：

func isRepoStarred(name: String) -> Observable<Bool> {
    URLSession.shared.rx.data(request: URLRequest(url: URL(string: "https://api.github.com/user/starred/\(name)")!))
        .map { data in
            var result = false
            // find out if repo is starred here and return true or false.
            return result
        }
}

這就是你的搜索。

func searchRepositories() -> Observable<RepositoryResponse> {
    var baseUrl = URLComponents(string: "https://api.github.com/search/repositories")   // base url
    let query = URLQueryItem(name: "q", value: "flutter")    // Keyword. flutter for this time.
    let sort = URLQueryItem(name: "sort", value: "stars")   // Sort by stars
    let order = URLQueryItem(name: "order", value: "desc")  // Desc order
    baseUrl?.queryItems = [query, sort, order]
    
    return URLSession.shared.rx.data(request: URLRequest(url: baseUrl!.url!))
        .map { data in
            try JSONDecoder().decode(RepositoryResponse.self, from: data)
        }
}

這就是您提出請求所需的全部內容。

要將它們結合起來，您可以這樣做：

let repositories = searchRepositories()
    .flatMap {
        Observable.zip($0.items.map { item in
            isRepoStarred(name: item.fullName).map { Repository(item, isStarred: $0) }
        })
    }

標籤：IOS 迅速 system.reactive rx-swift

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