下面的URLConnection有什么问题？ [英] What's wrong on following URLConnection?

问题描述

Objective-C使用Cookie的异步Web请求

我花了一天的时间写这个代码，任何人都可以告诉我这里有什么错误？

I spent a day writing this code and can anyone tell me what is wrong here?

WSHelper继承自NSObject，我甚至尝试NSDocument和NSObjectController和一切。

WSHelper is inherited from NSObject, I even tried NSDocument and NSObjectController and everything..

-(void) loadUrl: (NSString*) urlStr{
    url = [[NSURL alloc] initWithString:urlStr];
    request = [NSURLRequest requestWithURL:url cachePolicy: NSURLRequestReloadIgnoringCacheData timeoutInterval: 60.0];
    connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    if(connection)
    {
        receivedData = [[NSMutableData data] retain];
            //[connection start];
    }
    else
    {       display error etc...   }
    NSApplication * app = [NSApplication sharedApplication];
    [app runModalForWindow: waitWindow];// <-- this is the problem...
}

-(void)connection: (NSURLConnection*)connection didReceiveData:(NSData*)data{
    progressText = @"Receiving Data...";
    [receivedData appendData:data];
}

-(void)connection: (NSURLConnection *)connection didFailWithError:(NSError *)error{
    progressText = @"Error...";
    NSAlert * alert = [[NSAlert alloc] init];
    [alert setMessageText:[error localizedDescription]];
    [alert runModal];
}


- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
    progressText = @"Done...";
    pData = [[NSData alloc] initWithData:receivedData];
    [self hideWindow];
}

代码不会做任何事情，我甚至尝试它/没有startImmediately：YES但没有运气!!!，这是在主窗口中执行，所以即使线程和其运行循环正在成功运行。

The code just wont do anything, it doesnt progress at all. I even tried it with/without startImmediately:YES but no luck !!!, this is executed in main window so even the thread and its run loop is running successfully.

我试着调用同步请求，它是正常工作！但我需要async解决方案。

I tried calling synchronous request, and it is working correctly !! But I need async solution.

我在项目中添加了CoreServices.Framework，有什么更多我应该添加到项目？任何编译器设置？或者，在我可以使用NSURLConnection之前，我必须初始化任何东西？

I have added CoreServices.Framework in project, is there anything more I should be adding to the project? any compiler settings? Or do i have to initialize anything before I can use NSURLConnection?

任何解决方案运行NSURLConnection在不同的线程上自己的NSRunLoop，Objective-C和MAC开发没有样本

Any solution to run NSURLConnection on different thread on its own NSRunLoop, Objective-C and MAC Development has no sample code anywhere in documentation that makes everything so difficult to code.

推荐答案

首先，你要使连接开始太复杂。更改为：

Firstly you're making starting the connection too complicated. Change to:

connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]

删除 [连接开始] 。现在：

• 您的应用程序是否通常正常运行运行循环？


• 您可以执行网址请求的同步加载吗？


• 在调试器中，您可以看到 url 是你期望的吗？它是什么？


• 在收到任何委托消息之前，是否有可能释放WSHelper？ NSURLConnection毕竟是异步的。

• Is your app definitely running the run loop normally? NSURLConnection requires this to work.
• Are you able to perform a synchronous load of the URL request?
• In the debugger, can you see that url is what you expect it to be? What is it?
• Is it possible that you're deallocating WSHelper before any delegate messages are received? NSURLConnection is asynchoronous after all.

使用NSURLConnection不需要做任何特殊操作，这是Foundation框架的一个简单的部分。无需特殊的编译器设置。使用前无需初始化。没有。请不要盲目地尝试像引入CoreServices.Framework这样的东西。

One does not need to do anything special to use NSURLConnection, it's a straightforward part of the Foundation framework. No special compiler settings required. No initialization before use. Nothing. Please don't start blindly trying stuff like bringing in CoreServices.Framework.

由于同步发送请求的工作原理，你的处理异步方面肯定有问题。它可以是：

As sending the request synchronously works, there must be something wrong with your handling of the asynchronous aspect. It could be:

• runloop未在 NSDefaultRunLoopMode 中运行，因此连接是


• 您的代码的其他部分在连接上调用 -cancel ，然后才能加载。


• 您正在管理以在可以加载连接之前取消分配连接。

• The runloop is not running in NSDefaultRunLoopMode so the connection is unable to schedule itself.
• Some other part of your code is calling -cancel on the connection before it has a chance to load.
• You are managing to deallocate the connection before it has a chance to load.

啊，其实我刚刚意识到发生了什么。您正在呼叫：

Ah, in fact I've just realised what's going on. You are calling:

-[NSApp runModalForWindow:]

阅读此方法的说明。它不是运行 NSURLConnection 期望的运行循环。我会说，真的，你不想出现一个像这样的窗口，而运行一个URL连接。

Read the description of what this method does. It's not running the run loop like NSURLConnection expects. I'd say that really, you don't want to be presenting a window quite like this while running a URL connection for it.

我也建议你实现 -connection：didReceiveResponse：委托方法。您想在这里检查服务器是否返回预期的状态代码。

I'd also suggest that you implement the -connection:didReceiveResponse: delegate method too. You want to check here that the server is returning the expected status code.

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