Iphone 如何通知控制器下载已完成？

我有一个类可以下载带有NSURLConnection的图像。我是ios新手，所以我想知道如何“通知”我的ViewController下载已完成？我应该使用什么“工具”

澄清：

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我已经实现了NsUrlConnection的所有回调，我的问题是如何从我的ConnectionIDFinishLoading通知ViewController下载已完成？

我使用块来处理成功或失败的连接响应。它还有一个很好的包装器，用于检索图像并加载到UIImageView中。

要使用NSURLConnection，您必须实现一个委托，该委托具有在连接发生有趣的事情时调用的方法。这是您接收有关连接是否已建立、数据接收方式以及连接已完成的信息的方式（connectiondFinishLoading）。更多信息请访问

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因此，基本上，您放入连接的代码IDFinishLoading必须向视图控制器发送某种消息，以便它更新视图。

您应该在启动nsurl连接的类中使用以下方法：

#pragma mark -
#pragma mark Download support (NSURLConnectionDelegate)

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


- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error // Never called (deprecated method not used with IOS version >> 4.3 ???)
{
    // Clear the activeDownload property to allow later attempts
    self.activeDownload = nil;

    // Release the connection now that it's finished
    self.imageConnection = nil;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
    UIImage *image = [[UIImage alloc] initWithData:self.activeDownload];

    self.activeDownload = nil;
    // Release the connection now that it's finished
    self.imageConnection = nil;
}

NSURLConnection *imageConnection

其中imageConnection是NSURLConnection类型的属性：

#pragma mark -
#pragma mark Download support (NSURLConnectionDelegate)

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


- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error // Never called (deprecated method not used with IOS version >> 4.3 ???)
{
    // Clear the activeDownload property to allow later attempts
    self.activeDownload = nil;

    // Release the connection now that it's finished
    self.imageConnection = nil;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
    UIImage *image = [[UIImage alloc] initWithData:self.activeDownload];

    self.activeDownload = nil;
    // Release the connection now that it's finished
    self.imageConnection = nil;
}

NSURLConnection *imageConnection

而activeDownload是一个NSMutableData：

NSMutableData *activeDownload

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我不够具体，我已经实现了ConnectiondFinishLoading，并尝试了NSNotification向控制器发送通知，但从ConnectiondFinishLoading发送的通知在控制器中没有收到，可能是因为它在不同的线程中运行？我还能用什么？你是不是只是为了下载而使用线程？使用异步API会更容易。这样，您就可以通过普通的方法调用发送消息，比如

[controller imageDownloaded]

。在那里找到了我的解决方案。谢谢