ios - NSURLConnection didReceiveData 未加载数据

Question

我正在尝试从网站获取数据以将其显示在表格 View 中

我的代码:

-(void)loadTutorials {
    NSURL *url = [NSURL URLWithString:[@"http://www.example.com/search?q=" stringByAppendingString:self.searchString]];
    NSURLRequest *UrlString = [[NSURLRequest alloc] initWithURL:url];

    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:UrlString
                                                          delegate:self];

    [connection start];
    NSLog(@"Started");

}


- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
        TFHpple *tutorialsParser = [TFHpple hppleWithHTMLData:data];

        NSString *tutorialsXpathQueryString = @"//div[@id='header']/div[@class='window']/div[@class='item']/div[@class='title']/a";
        NSArray *tutorialsNodes = [tutorialsParser searchWithXPathQuery:tutorialsXpathQueryString];

        NSMutableArray *newTutorials = [[NSMutableArray alloc] init];

        for (TFHppleElement *element in tutorialsNodes) {

            Data *tutorial = [[Data alloc] initWithTitle: [[element firstChild] content]
                                                     Url: [@"http://www.example.com" stringByAppendingString: [element objectForKey:@"href"]]
                              ];

            [newTutorials addObject:tutorial];


        }

        _objects = newTutorials;
        [self.tableView reloadData];


}

但是数据没有显示出来，是不是数据没有加载完？我让它在没有 NSURLConnection 的情况下工作，但是它会停止程序直到收到数据

Answer 1

根据 NSURLConnectionDataDelegate

connection:didReceiveData:

以增量方式调用。

The newly available data. The delegate should concatenate the contents of each data object delivered to build up the complete data for a URL load.

所以这意味着您应该在此方法中附加新数据。

然后，在

- (void)connectionDidFinishLoading:(NSURLConnection *)connection

您应该操纵您的数据。

所以，例如

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    // Create space for containing incoming data
    // This method may be called more than once if you're getting a multi-part mime
    // message and will be called once there's enough date to create the response object
    // Hence do  a check if _responseData already there
    _responseData = [[NSMutableData alloc] init];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    // Append the new data
    [_responseData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    // Parse the stuff in your instance variable now    
}

显然，您还应该实现负责错误处理的委托(delegate)。

下面是一个简单的注释。如果数据太大并且你需要做一些计算(例如解析)，你可以阻止 UI。所以，你可以在不同的线程中移动解析(GCD 是你的 friend )。完成后，您可以在主线程中重新加载表格。

也可以在这里查看更多信息:NSURLConnectionDataDelegate order of functions .