[英]Swift 3 URLSession with URLCredential not working
我正在執行URLSession,但是URL需要憑據。
我這里有整個方法,試圖用URLCredentials做一個URLSession:
func loginUser(_ username: String, password: String, completion: @escaping (_ result: Bool) -> Void)
{
//Create request URL as String
let requestString = String(format:"%@", webservice) as String
//Covert URL request string to URL
guard let url = URL(string: requestString) else {
print("Error: cannot create URL")
return
}
//Convert URL to URLRequest
let urlRequest = URLRequest(url: url)
print(urlRequest)
//Add the username and password to URLCredential
credential = URLCredential(user:username, password:password, persistence: .forSession)
//Setup the URLSessionConfiguration
let config = URLSessionConfiguration.default
//Setup the URLSession
let session = URLSession(configuration: config, delegate: self, delegateQueue: nil)
//Prepare the task to get data.
let task = session.dataTask(with: urlRequest, completionHandler: { (data, response, error) in
DispatchQueue.main.async(execute: {
if(error == nil)
{
completion(true)
}
else
{
completion(false)
}
})
})
//Run the task to get data.
task.resume()
}
這是我的URLSessionDelegate方法:
func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
if challenge.previousFailureCount > 0
{
completionHandler(Foundation.URLSession.AuthChallengeDisposition.cancelAuthenticationChallenge, nil)
}
else
{
completionHandler(Foundation.URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust:challenge.protectionSpace.serverTrust!))
}
}
/**
Requests credentials from the delegate in response to an authentication request from the remote server.
*/
func urlSession(_ session: URLSession, task: URLSessionTask, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
completionHandler(Foundation.URLSession.AuthChallengeDisposition.useCredential,credential)
}
我注意到在此委托方法中調試此代碼時:
func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
if challenge.previousFailureCount > 0
{
completionHandler(Foundation.URLSession.AuthChallengeDisposition.cancelAuthenticationChallenge, nil)
}
else
{
completionHandler(Foundation.URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust:challenge.protectionSpace.serverTrust!))
}
}
該方法被調用兩次,並且第二次到達該行時:
completionHandler(Foundation.URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust:challenge.protectionSpace.serverTrust!))
我收到此錯誤:
fatal error: unexpectedly found nil while unwrapping an Optional value
然后我的應用崩潰了! 如何解決此錯誤?
崩潰是由於在您嘗試強行打開包裝時, challenge.protectionSpace.serverTrust
為零。
您應該解開serverTrust
並將其處理為nil。 我的猜測是,當serverTrust
為零challenge.error
有一個值。
func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
if challenge.previousFailureCount > 0 {
completionHandler(Foundation.URLSession.AuthChallengeDisposition.cancelAuthenticationChallenge, nil)
} else if let serverTrust = challenge.protectionSpace.serverTrust {
completionHandler(Foundation.URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust: serverTrust))
} else {
print("unknown state. error: \(challenge.error)")
// do something w/ completionHandler here
}
}
這是每個Swift 3的語法。
只需首先驗證它在委托方法的哪一部分輸入
open func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Swift.Void){
var disposition: URLSession.AuthChallengeDisposition = URLSession.AuthChallengeDisposition.performDefaultHandling
var credential:URLCredential?
if challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust {
credential = URLCredential(trust: challenge.protectionSpace.serverTrust!)
if (credential != nil) {
disposition = URLSession.AuthChallengeDisposition.useCredential
}
else{
disposition = URLSession.AuthChallengeDisposition.performDefaultHandling
}
}
else{
disposition = URLSession.AuthChallengeDisposition.cancelAuthenticationChallenge
}
if (completionHandler != nil) {
completionHandler(disposition, credential);
}
}
這是從上面的答案中略微重構而成的,委托類檢查失敗的數量,使用默認值,除非質詢是服務器信任類型,然后使用信任憑證調用完成:
class AuthSessionDelegate: NSObject, URLSessionDelegate {
func urlSession(_ session: URLSession,
didReceive challenge: URLAuthenticationChallenge,
completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
let authMethod = challenge.protectionSpace.authenticationMethod
guard challenge.previousFailureCount < 1, authMethod == NSURLAuthenticationMethodServerTrust,
let trust = challenge.protectionSpace.serverTrust else {
completionHandler(.performDefaultHandling, nil)
return
}
completionHandler(.useCredential, URLCredential(trust: trust))
}
}
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