如何使用NSURLConnection下载文件？ [英] How to download a file by using NSURLConnection?

问题描述

我想问一个关于目标C的问题。我想从iPhone应用程序中的服务器（CardDav服务器）下载.vcf文件。在我阅读了Apple Developer的API和库之后，我发现我应该使用 NSURLConnection类。但是，我不知道如何启动该程序。

I want to ask a question about the objective C. I want to download a .vcf file from a server (CardDav server) in iPhone application. After I read the API and library of the Apple Developer, I found that I should use the NSURLConnection Class. However, I don't know how to start the program.

因此，我想问一下，任何人都可以给我一些教程或网站参考（我的意思是这个例子）我？非常感谢。

Therefore, I want to ask can anyone give me some tutorial or website reference (I mean the example) for me? Thank you very much.

推荐答案

您可以使用此方法：

- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately:(BOOL)startImmediately

More here
and delegate：

More here and the delegate:

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response

- (void)connectionDidFinishLoading:(NSURLConnection *)connection

委托是一个对象，可以响应上述两种方法来接收数据。如果要进行异步，则必须使用委托。如果你不这样做，你可以这样做：

The delegate is an object that can respond to 2 above methods to receive the data. If you want to do asynchronous, you have to use delegate. If you don't, you can just do:

+ (NSData *)sendSynchronousRequest:(NSURLRequest *)request returningResponse:(NSURLResponse **)response error:(NSError **)error

[More here][2]

或者你可以这样做一些数据：

Or you can just do like this for some data:

+ (id)dataWithContentsOfURL:(NSURL *)aURL

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