带有 Cookie 的 Objective-C 异步 Web 请求

Question

我正在用 Objective-C 编写一个程序，我需要向 web 服务器发出 web 请求，但是异步的，我在 mac 上相当新，我非常擅长 windows 技术，但我需要知道如果我使用NSOperation（在 10.5 中引入，我假设它不会在 10.4 MAC 中运行？），或者如果它被实现为利用 10.4 上可用的系统线程？

或者我应该创建一个新线程并创建一个新的runloop，以及如何使用cookie等，如果有人能给我一个小例子，那将有很大帮助。如果可能的话，我希望这个示例也能在 mac 10.4 上运行。

Answer 1

有一个很好的例子，使用 NSURLRequest 和 NSHTTPCookies 来做一个完整的 web 应用程序示例，登录到一个网站，存储 SessionID cookie 并在以后的请求中重新提交它。

NSURLConnection, NSHTTPCookie

通过 logix812：

    NSHTTPURLResponse   * response;
    NSError             * error;
    NSMutableURLRequest * request;
    request = [[[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://temp/gomh/authenticate.py?setCookie=1"]
                                            cachePolicy:NSURLRequestReloadIgnoringCacheData 
                                        timeoutInterval:60] autorelease];

    [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];  
    NSLog(@"RESPONSE HEADERS: \n%@", [response allHeaderFields]);

    // If you want to get all of the cookies:
    NSArray * all = [NSHTTPCookie cookiesWithResponseHeaderFields:[response allHeaderFields] forURL:[NSURL URLWithString:@"http://temp"]];
    NSLog(@"How many Cookies: %d", all.count);
    // Store the cookies:
    // NSHTTPCookieStorage is a Singleton.
    [[NSHTTPCookieStorage sharedHTTPCookieStorage] setCookies:all forURL:[NSURL URLWithString:@"http://temp"] mainDocumentURL:nil];

    // Now we can print all of the cookies we have:
    for (NSHTTPCookie *cookie in all)
        NSLog(@"Name: %@ : Value: %@, Expires: %@", cookie.name, cookie.value, cookie.expiresDate); 


    // Now lets go back the other way.  We want the server to know we have some cookies available:
    // this availableCookies array is going to be the same as the 'all' array above.  We could 
    // have just used the 'all' array, but this shows you how to get the cookies back from the singleton.
    NSArray * availableCookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:[NSURL URLWithString:@"http://temp"]];
    NSDictionary * headers = [NSHTTPCookie requestHeaderFieldsWithCookies:availableCookies];

    // we are just recycling the original request
    [request setAllHTTPHeaderFields:headers];

    request.URL = [NSURL URLWithString:@"http://temp/gomh/authenticate.py"];
    error       = nil;
    response    = nil;

    NSData * data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
    NSLog(@"The server saw:\n%@", [[[NSString alloc] initWithData:data encoding: NSASCIIStringEncoding] autorelease]);

Answer 2

对于异步请求，需要使用NSURLConnection。

有关 Cookie，请参阅 NSHTTPCookie 和 NSHTTPCookieStorage。

更新：

下面的代码是来自我的一个应用程序的真实有效代码。 responseData在类接口中定义为NSMutableData*。

- (void)load {
    NSURL *myURL = [NSURL URLWithString:@"http://stackoverflow.com/"];
    NSURLRequest *request = [NSURLRequest requestWithURL:myURL
                                             cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                         timeoutInterval:60];
    [[NSURLConnection alloc] initWithRequest:request delegate:self];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    responseData = [[NSMutableData alloc] init];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [responseData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    [responseData release];
    [connection release];
    // Show error message
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    // Use responseData
    [responseData release];
    [connection release];
}

Answer 3

我可以通过这种方式获取 cookie：

NSArray* arr = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:[NSURL URLWithString: @"http://google.com" ]];

这也适用于异步请求。