Question

我正在开发一个连接到服务器并从中下载数据的项目。如果连接中断，我想支持简历下载。我的方法是将下载的数据部分保存到目标文件中;如果连接中断，我想使用connection标记下载的部分：didWriteData：totalBytesWritten：expectedTotalBytes以及稍后从服务器停止的部分恢复。

我的代码：

- (IBAction)connectToServer:(UIButton *)sender
{
    // setup url and send request to server
    NSURL *url = [NSURL URLWithString:BASED_URL];
    self.urlRequest = [[NSMutableURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
    self.urlConnection = [[NSURLConnection alloc] initWithRequest:self.urlRequest delegate:self];

    // start receive data if connection established
    if (self.urlConnection){
    self.receivedData = [NSMutableData data];
    NSLog(@"starting to receive data");

} else {
    // handle error
    NSLog(@"failed to connect to server");
    }
}

- (void)doSomethingWithData
{
    // handle data here
}


#pragma NSURLConnectionDataDelegate

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse     *)response
{
    [self.receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    // received data
    [self.receivedData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    // error connection
    NSLog(@"connection failed");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"Data receiving succeed, received: %d bytes of data", [self.receivedData length]);

}

- (void)connection:(NSURLConnection *)connection didWriteData:(long long)bytesWritten totalBytesWritten:(long long)totalBytesWritten expectedTotalBytes:(long long)expectedTotalBytes
{
    NSLog(@"not getting called");
}

我的问题是如何才能调用“connection：didWriteData：totalBytesWritten：expectedTotalBytes”方法？

非常感谢！克里斯

Answer 1

你在.h文件中添加了这个：

 @interface yourViewContoller : UIViewController <NSURLConnectionDataDelegate, NSURLConnectionDelegate>

Answer 2

根据Apple's documentation：

NSURLConnectionDownloadDelegate协议描述了应该使用Newsstand Kit的downloadWithDelegate：方法创建的NSURLConnection实例的委托实现的方法。

另外，它说：

如果您直接使用NSURLConnection，您的委托类应该实现NSURLConnectionDataDelegate协议中定义的方法。

NSURLConnectionDownloadDelegate方法未被调用

2 个答案: