Cocoa notes (25) Networking

星期五, 六月 3rd, 2011

创建连接

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// Create the request.
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.apple.com/"]
                        cachePolicy:NSURLRequestUseProtocolCachePolicy
                    timeoutInterval:60.0];
// create the connection with the request
// and start loading the data
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

if (theConnection) {
    // Create the NSMutableData to hold the received data.
    // receivedData is an instance variable declared elsewhere.
    receivedData = [[NSMutableData data] retain];
} else {
    // Inform the user that the connection failed.
}

连接在initWithRequest:delegate:一执行就开始下载了。

代理方法处理各个状态
收到response

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- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    // This method is called when the server has determined that it
    // has enough information to create the NSURLResponse.

    // It can be called multiple times, for example in the case of a
    // redirect, so each time we reset the data.

    // receivedData is an instance variable declared elsewhere.
    [receivedData setLength:0];

}

收到数据

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- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    // Append the new data to receivedData.
    // receivedData is an instance variable declared elsewhere.
    [receivedData appendData:data];
}

连接错误

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- (void)connection:(NSURLConnection *)connection
  didFailWithError:(NSError *)error
{
    // release the connection, and the data object
    [connection release];

    // receivedData is declared as a method instance elsewhere
    [receivedData release];

    // inform the user
    NSLog(@"Connection failed! Error - %@ %@",
          [error localizedDescription],
          [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}

连接结束

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- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    // do something with the data
    // receivedData is declared as a method instance elsewhere
    NSLog(@"Succeeded! Received %d bytes of data",[receivedData length]);

    // release the connection, and the data object
    [connection release];
    [receivedData release];
}

NSURLDownload可以把数据直接下载到磁盘

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- (void)startDownloadingURL:sender
{
    // Create the request.
    NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.apple.com"]
                                              cachePolicy:NSURLRequestUseProtocolCachePolicy
                                          timeoutInterval:60.0];

 
    // Create the connection with the request and start loading the data.
NSURLDownload  *theDownload = [[NSURLDownload alloc] initWithRequest:theRequest
                                             delegate:self];
    if (theDownload) {
        // Set the destination file.
        [theDownload setDestination:@"/tmp" allowOverwrite:YES];
    } else {
        // inform the user that the download failed.
    }
}

- (void)download:(NSURLDownload *)download didFailWithError:(NSError *)error
{
    // Release the connection.
    [download release];

    // Inform the user.
    NSLog(@"Download failed! Error - %@ %@",
          [error localizedDescription],
          [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}


- (void)downloadDidFinish:(NSURLDownload *)download
{
    // Release the connection.
    [download release];
 
    // Do something with the data.
    NSLog(@"%@",@"downloadDidFinish");
}

Downloading a File Using the Suggested Filename

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- (void)startDownloadingURL:sender
{
    // Create the request.
    NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.apple.com/index.html"]
                                             cachePolicy:NSURLRequestUseProtocolCachePolicy
                                             timeoutInterval:60.0];

 
    // Create the download with the request and start loading the data.
NSURLDownload  *theDownload = [[NSURLDownload alloc] initWithRequest:theRequest delegate:self];
    if (!theDownload) {
        // Inform the user that the download failed.
    }
}

- (void)download:(NSURLDownload *)download decideDestinationWithSuggestedFilename:(NSString *)filename
{
    NSString *destinationFilename;
    NSString *homeDirectory = NSHomeDirectory();

    destinationFilename = [[homeDirectory stringByAppendingPathComponent:@"Desktop"]
        stringByAppendingPathComponent:filename];
    [download setDestination:destinationFilename allowOverwrite:NO];
}

- (void)download:(NSURLDownload *)download didFailWithError:(NSError *)error
{
    // Release the download.
    [download release];

    // Inform the user.
    NSLog(@"Download failed! Error - %@ %@",
          [error localizedDescription],
          [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}

- (void)downloadDidFinish:(NSURLDownload *)download
{
    // Release the download.
    [download release];

    // Do something with the data.
    NSLog(@"%@",@"downloadDidFinish");
}

控制Response Cache

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-(NSCachedURLResponse *)connection:(NSURLConnection *)connection
                 willCacheResponse:(NSCachedURLResponse *)cachedResponse
{
    NSCachedURLResponse *newCachedResponse = cachedResponse;

    if ([[[[cachedResponse response] URL] scheme] isEqual:@"https"]) {
        newCachedResponse = nil;
    } else {
        NSDictionary *newUserInfo;
        newUserInfo = [NSDictionary dictionaryWithObject:[NSCalendarDate date]
                                                 forKey:@"Cached Date"];
        newCachedResponse = [[[NSCachedURLResponse alloc]
                                initWithResponse:[cachedResponse response]
                                    data:[cachedResponse data]
                                    userInfo:newUserInfo
                                    storagePolicy:[cachedResponse storagePolicy]]
                            autorelease];
    }
    return newCachedResponse;
}

监控上传进度
connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:

如果要使用同步传输，使用
+ sendSynchronousRequest:returningResponse:error:

处理redirect

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-(NSURLRequest *)connection:(NSURLConnection *)connection
            willSendRequest:(NSURLRequest *)request
           redirectResponse:(NSURLResponse *)redirectResponse
{
    NSURLRequest *newRequest = request;
    if (redirectResponse) {
        newRequest = nil;
    }
    return newRequest;
}

HTTP验证
如果request http地址需要http验证，会调用connection:canAuthenticateAgainstProtectionSpace:

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-(void)connection:(NSURLConnection *)connection
        didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
    if ([challenge previousFailureCount] == 0) {
        NSURLCredential *newCredential;
        newCredential = [NSURLCredential credentialWithUser:[self preferencesName]
                                                 password:[self preferencesPassword]
                                              persistence:NSURLCredentialPersistenceNone];
        [[challenge sender] useCredential:newCredential
               forAuthenticationChallenge:challenge];
    } else {
        [[challenge sender] cancelAuthenticationChallenge:challenge];
        // inform the user that the user name and password
        // in the preferences are incorrect
        [self showPreferencesCredentialsAreIncorrectPanel:self];
    }
}

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