如何驗證是否可以使用Swift訪問網站？-有解無憂

我的應用程式應訪問托管網站上的 php 檔案，以便從后端 SQL 資料庫獲取資料。這作業正常，但我想做好準備或所有可能的錯誤。如果沒有互聯網連接或無法訪問主機，則會引發錯誤 - 很好。但是如果將 url 地址修改為主機上不存在的地址，則不會拋出錯誤。但我也想涵蓋這種情況。Swift 中最好的方法是什么？

這是我的代碼：

    @available(iOS 15.0, *)
   func checkCustomerExistsInBackend(emailAddress: String) async throws -> String 
   {
    
    let url = URL(string: "https://myHost.de/mySite/checkCustomerexists.php")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    
    let dataString = "EmailAddress=\(emailAddress)"
    var returnValue = ""
    do {
        let dataD = dataString.data(using: .utf8)
        let (data, _) = try await URLSession.shared.upload(for: request, from: dataD!, delegate: nil)
        let answer = try JSONDecoder().decode(BackendMessage.self, from: data)
        returnValue = answer.Message
    }
    catch {
        let myError: NSError = error as NSError
        switch myError.localizedDescription {
        case "The Internet connection appears to be offline.":
            throw BackendError.noInternet
        case "A server with the specified hostname could not be found.":
            throw BackendError.serverNotFound
        default:
            throw error
        }
    }
    return returnValue
}

上面帶有“https://myHost.de/mySite/checkCustomerexists.php”的網址當然不是真實地址。但是，當我用真實的主機地址替換“myHost.de”時，即使站點“mySite”不存在，也不會引發錯誤。

我花了幾個小時在 SO 中尋找答案，但找不到任何適合我的星座的東西。

任何提示將不勝感激！

uj5u.com熱心網友回復：

Larme 的評論回答了這個問題。如果它對任何跨過同一主題的人有幫助，這里是我的示例的修改代碼以及基于 Larme 建議的解決方案：

   @available(iOS 15.0, *)
func checkCustomerExistsInBackend(emailAddress: String) async throws -> String {
    
    let url = URL(string: "https://myHost.de/mySite/checkCustomerexists.php")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    
    let dataString = "EmailAddress=\(emailAddress)"
    var returnValue = ""
    do {
        let dataD = dataString.data(using: .utf8)
        let (data, response) = try await URLSession.shared.upload(for: request, from: dataD!, delegate: nil)
       
        let httpURLResponse = response as? HTTPURLResponse
        let statusCode = httpURLResponse?.statusCode
        if statusCode != 404 {
            let answer = try JSONDecoder().decode(BackendMessage.self, from: data)
            returnValue = answer.Message
        }
        else {
            throw BackendError.invalidURL
        }
    }
    catch {
        let myError: NSError = error as NSError
        print(myError.localizedDescription)
        switch myError.localizedDescription {
        case "The Internet connection appears to be offline.":
            throw BackendError.noInternet
        case "A server with the specified hostname could not be found.":
            throw BackendError.serverNotFound
        default:
            throw error
        }
    }
    return returnValue
}

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