检查NSURLSessionDataTask的响应值

Question

我是iOS开发人员的完全新手，并且正在处理我的第一个应用程序。我正在与需要用户使用其用户名和密码登录的Web服务进行交互。我想检查并确保它们在输入正确的用户名和密码之前将其保存在钥匙串中，因此我使用凭据进行了简单的获取请求。我想检查我收到的回复，看看是否收到错误消息。这里是我写的代码，它对Web服务执行GET请求。

-(BOOL)checkCredentials:(NSString *)username withPassword:(NSString *)password{ 

    NSString *requestString = @"some_web_service_url"; 
    NSURL *url = [NSURL URLWithString:requestString]; 
    NSURLRequest *req = [NSURLRequest requestWithURL:url]; 

    NSData *userPasswordData = [[NSString stringWithFormat:@"%@:%@", username, password] dataUsingEncoding:NSUTF8StringEncoding]; 
    NSString *base64EncodedCredential = [userPasswordData base64EncodedStringWithOptions:0]; 
    NSString *authString = [NSString stringWithFormat:@"Basic %@", base64EncodedCredential]; 

    NSURLSessionConfiguration *sessionConfig=[NSURLSessionConfiguration defaultSessionConfiguration]; 
    sessionConfig.HTTPAdditionalHeaders=@{@"Authorization":authString}; 

    self.session=[NSURLSession sessionWithConfiguration:sessionConfig]; 

    NSURLSessionDataTask *dataTask = [self.session dataTaskWithRequest:req completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) { 
     NSMutableDictionary *jsonObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil]; 

     NSLog(@"%@", jsonObject); 

    }]; 

    [dataTask resume]; 
    //I think error checking logic should go here. 
} 

我想检查我的jsonObject的错误代码，但我能做到这一点我做[dataTask resume]后？有没有更好的方法来检查返回码？我相信jsonObject将返回JSON，所以我想我想检查头的返回值，但我不完全确定。对不起，如果这是一个简单的问题，但我是新的，有点困惑。任何帮助将不胜感激！

Answer 1

您可以通过在会话数据任务完成块中将NSURLResponse转换为NSHTTPURLResponse来检索HTTP返回码，并检查statusCode属性。

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    NSString *user;   // Update to your user name 
    NSString *password;  // Update to your use name password 

    [self checkCredentials:user withPassword:password completion:^(BOOL authorized) { 
     if (authorized) { 
      // Save the credentials 

      dispatch_async(dispatch_get_main_queue(), ^{ 
       // Update your UI if needed. 
      }); 
     } else { 
      // Unauthorized 
      // 
      // Inform the user if needed. 
     } 
    }]; 
} 

- (void)checkCredentials:(NSString *)username 
      withPassword:(NSString *)password 
       completion:(void (^)(BOOL))authorized 
{ 
    NSString *requestString; // Update to your Web Service URL 
    NSURL *url = [NSURL URLWithString:requestString]; 
    NSURLRequest *req = [NSURLRequest requestWithURL:url]; 

    NSData *userPasswordData = [[NSString stringWithFormat:@"%@:%@", username, password] dataUsingEncoding:NSUTF8StringEncoding]; 
    NSString *base64EncodedCredential = [userPasswordData base64EncodedStringWithOptions:0]; 
    NSString *authString = [NSString stringWithFormat:@"Basic %@", base64EncodedCredential]; 

    NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration]; 
    sessionConfig.HTTPAdditionalHeaders = @{ @"Authorization" : authString }; 
    self.session = [NSURLSession sessionWithConfiguration:sessionConfig]; 

    NSURLSessionDataTask *dataTask = 
    [self.session dataTaskWithRequest:req completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) { 

     NSHTTPURLResponse *httpURLResponse = (NSHTTPURLResponse *)response; 
     NSUInteger statusCode = httpURLResponse.statusCode; 

     switch (statusCode) { 
      case 200:     // Authorized 
       authorized(YES); 
       break; 
      case 401:     // Unauthorized 
       authorized(NO); 
       break; 
      default: 
       // Unauthorized 
       // 
       // For a copmlete list of HTTP response status codes see http://www.ietf.org/rfc/rfc2616.txt 
       // also be aware that not all Web Services return the same status codes. 
       authorized(NO); 
       break; 
     } 
    }]; 

    [dataTask resume]; 
}