Cocoa HTTP POST 请求 [Mac OS X]

Question

我花了很多时间研究使用 Cocoa 的 POST 请求。

我发现了一些看起来不错的代码。我改变了它，就像它适合我的需要一样。但是代码不起作用，我找不到错误，因为我对可可很陌生。

这是我的代码。

- (IBAction)sendForm:(id)sender
{
    NSLog(@"web request started");
    NSString *post = [NSString stringWithFormat:@"firstName=%@&lastName=%@&eMail=%@&message=%@", firstName.stringValue, lastName.stringValue, eMail.stringValue, message.stringValue];
    NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
    NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];

    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
    [request setURL:[NSURL URLWithString:@"myDomain/form.php"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:postData];

    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    if(theConnection)
    {
        webData = [[NSMutableData data] retain];
        NSLog(@"connection initiated");
    }
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [webData appendData:data];
    NSLog(@"connection received data");
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"connection received response");
    NSHTTPURLResponse *ne = (NSHTTPURLResponse *)response;
    if([ne statusCode] == 200)
    {
        NSLog(@"connection state is 200 - all okay");
        NSString *html = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding];
        [[webView mainFrame] loadHTMLString:html baseURL:[NSURL URLWithString:@"myDomain"]];
    }
}

但我收到的仅有的两条 NSLog 消息是“网络请求已启动”和“连接已启动”。 所以我认为- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 和- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 没有被调用。

谁能帮我解决这个问题？

谢谢你的帮助，朱利安

Answer 1

你几乎做对了！

我可以看到这篇文章已经有一年了，但希望它可以帮助其他人并作为我自己的参考，我在这里发布。

Apple 的 connection:didReceiveResponse: 文档说：-

当连接接收到足够的数据来构建 其请求的 URL 响应。

与大多数 Apple 文档一样，这也令人困惑并且可能具有误导性。通常当我们有“足够的数据来构造 URL 响应”意味着我们有完整的响应，这进一步意味着我们也有响应体；这被普遍认为是响应的一部分。

但是在这种情况下，NSHTTPURLResponse 对象没有主体。所以我的猜测是，Apple 的意思是——connection:didReceiveResponse: 在我们收到包含“足够”数据的响应头时被调用，让我们知道除了实际数据（正文）之外的所有关于响应的信息。

事实上很多时候你会注意到connection:didReceiveData:在connection:didReceiveResponse:被调用之后被调用。

所以，我们可以修改您的代码如下：-

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {

    NSLog(@"web request started");
    NSString *post = [NSString stringWithFormat:@"firstName=%@&lastName=%@&eMail=%@&message=%@", firstName.stringValue, lastName.stringValue, eMail.stringValue, message.stringValue];
    NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding];
    NSString *postLength = [NSString stringWithFormat:@"%ld", (unsigned long)[postData length]];

    NSLog(@"Post data: %@", post);

    NSMutableURLRequest *request = [NSMutableURLRequest new];
    [request setURL:[NSURL URLWithString:@"https://example.com/form.php"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:postData];

    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

    if(theConnection) {
        webData = [NSMutableData data];
        NSLog(@"connection initiated");
    }
}

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

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"connection received response");
    NSHTTPURLResponse *ne = (NSHTTPURLResponse *)response;
    if([ne statusCode] == 200) {
        NSLog(@"connection state is 200 - all okay");
    } else {
        NSLog(@"connection state is NOT 200");
    }
}

-(void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"Conn Err: %@", [error localizedDescription]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    NSLog(@"Conn finished loading");
    NSString *html = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding];
    NSLog(@"OUTPUT:: %@", html);
}

Answer 2

您是否尝试过实现错误委托方法？

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    // do something with error
}

在NSURLConnection 能够建立连接之前，您可能没有互联网连接，或者出现其他问题。在这种情况下，您将不会收到 http 响应或任何其他数据。该错误将提供更多信息。

[编辑]

我刚刚注意到示例代码中的 URL 不包含主机名。如果这是您使用的确切代码，请确保将请求发送到正确的 URL。

// Replace
[NSURL URLWithString:@"myDomain/form.php"]
// with a correct url like
[NSURL URLWithString:@"http://mydomain.com/form.php"];

错误委托方法实际上会为您提供一个抱怨错误 URL 的错误。