iphone - 在 iPhone 中发布 URL 时，连接 didReceiveData 调用了两次？

Question

我是 iPhone 开发新手。我已经发布了带有用户名和密码的 URL。我可以在“connection didReceiveData”方法中打印数据。但是我看到“connection didReceiveData”方法被调用了两次。我不知道我哪里出错了。这是我的代码

 - (void)viewDidLoad {
[super viewDidLoad];

NSString *post = [NSString stringWithFormat:@"&domain=school.edu&userType=2&referrer=http://apps.school.edu/navigator/index.jsp&username=%@&password=%@",@"xxxxxxx",@"xxxxxx"];

NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];

NSString *postLength = [NSString stringWithFormat:@"%d",[postData length]];

NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];

[request setURL:[NSURL URLWithString:[NSString stringWithFormat:@"https://secure.school.edu/login/process.do"]]];

[request setHTTPMethod:@"POST"];

[request setValue:postLength forHTTPHeaderField:@"Content-Length"];

[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Current-Type"];

[request setHTTPBody:postData];

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

if(conn)
{
    NSLog(@"Connection Successful");

}
else
{
    NSLog(@"Connection could not be made");
}

    }

 - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data{

NSString *string = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(@"the  data %@",string);
  }

整个 HTML 页面在控制台中打印了两次。所以请帮助我。谢谢。

Answer 1

您可能会收到分块的响应数据，这就是 NSURLConnection's documentation 的原因状态:

“委托(delegate)应该连接所交付的每个数据对象的内容，以构建 URL 加载的完整数据。”

为此使用 NSMutableData 实例，并且仅在收到 -connectionDidFinishLoading: 消息后才处理完整数据。