Question

我们的要求包括检查对Web服务器上特定文件的Internet访问。每隔 n 分钟检查此文件。 NSURLRequests 从不调用connection：didFailWithError是否存在互联网连接。并且HTTP状态始终为200. Apple的可访问性仅适用于域，而不适用于文件 - 因此它不符合要求。如何可靠地发现我是否可以每隔 n 分钟到达此文件？为什么http状态代码真的不是http状态代码？

似乎回答这个问题的其他stackoverflow问题不起作用：
1. How could connectionDidFinishLoading: run if no file is found on server?
2. Testing use of NSURLConnection with HTTP response error statuses

我尝试使用另一个带有完成块的队列，但这也无效。

-(void) updateConnectionStatus 
{   
    NSURL *url = [NSURL URLWithString:(NSString*)[appValues getValueForSettingsKey:@"company.project.test.pingURL"]];
    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url];
    //NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    //__block __typeof__(self) _self = self;
    connection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self];
 /*
    [NSURLConnection
    sendAsynchronousRequest:urlRequest queue:queue
        completionHandler:^(NSURLResponse *response,
                         NSData *data,
                         NSError *error) {

         NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse*)response;
         int code = [httpResponse statusCode]; // ALWAYS 200 no matter what
         NSString *pingFile = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
         NSLog(@"%@",error); // NEVER has an error
         //This doesn't even work because it remembers FOREVER the value once it gets it.
         if ([@"Ping!" isEqualToString:pingFile])  
         {
             dispatch_async(dispatch_get_main_queue(), ^{                     
                 [_self companyConnection:YES];                     
             });                 
         } else {
             dispatch_async(dispatch_get_main_queue(), ^{                     
                 [_self companyConnection:NO];                     
             });
         }         
     }];
      */
}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"ERROR:  %@", error); // Never get here 
}

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSHTTPURLResponse *aResponse = (NSHTTPURLResponse*)response;
    NSLog(@"received a response: %ld",(long)[aResponse statusCode] );
    if ([response respondsToSelector:@selector(statusCode)])
    {
        int statusCode = [((NSHTTPURLResponse *)response) statusCode];
        // statusCode is always 200
        if (statusCode >= 400)
        {
            [companyConnection cancel];  // stop connecting; no more delegate messages
            NSDictionary *errorInfo
            = [NSDictionary dictionaryWithObject:[NSString stringWithFormat:
                                                  NSLocalizedString(@"Server returned status code %d",@""),
                                                  statusCode]
                                          forKey:NSLocalizedDescriptionKey];
        }
    }
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"received data");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"Finished");        
}

Answer 1

尝试在构造NSURLRequest对象时将cachePolicy设置为NSURLRequestReloadIgnoringCacheData

Answer 2

感谢Wain和Rob让我走上了正确的道路。保持缓存清晰的一种方法是将此方法添加到NSURLConnectionDelegate：

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse
{
    return nil;
}

iOS NSURLRequests状态代码始终为200

2 个答案: