3

我认为我已经编辑了这篇文章以使其更易于阅读。

在 dispatch_async 块中完成一些密集的字符串操作后，我需要调用 NSUrlConnection。

我调用的 URL 有 .htaccess 身份验证，所以我不能使用同步连接。

但是没有调用 NSURLConnection 委托方法。我知道 URL 在浏览器中大约 5 秒后加载，并且我已经使用没有身份验证的简单 URL 测试了代码，它没有任何区别。

是什么阻止了委托方法被调用？

这个函数做了一些字符串操作，需要一段时间才能完成：

- (void)performSearch {

    // set some defaults and work out if it is a valid search, setting bSearchOk

    if (bSearchOk) {

        // update some interface elements
        self.msgBox.text = @"Translating...";            
        self.plateInput.enabled = NO;
        self.searchProgress.hidden = NO;

        dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

            // create a new search
            Search *oPlateSearch = [[Search alloc] initWithTerm:thisTerm];

            // ...
            // perform search... this calls a variety of slow and intensive functions
            // ...

            self.aFinalPlates = [oPlateSearch.aValidated copy];
            self.aCurrentPlates = [oPlateSearch.aFinals copy];        

            dispatch_async( dispatch_get_main_queue(), ^{                 
                [oPlateSearch release];              

                // make ajax call to check if plates can be bought
                [self getPrices];                 
            });
        });

    } else {
        // hide results
        self.searchResults.hidden = YES;
    }

}

这是在上面的块末尾调用的那个

/* call to get plate availability and prices */
-(void) getPrices {
    // set return message
    self.msgBox.text = @"Getting prices and availability";

    // ...
    // then I build my strRequest var, which is a valid working URL
    // ...

    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:strRequest]];

    NSURLConnection *loginConnection = [[[NSURLConnection alloc] initWithRequest:request delegate:self] autorelease];

    NSLog('This will get logged');

    if(loginConnection) {
        NSLog('This will also get logged');
        self.jsonSearchResponse = [[[NSMutableData data] retain] autorelease];
        NSLog('And this will get logged, so it's not throwing errors');
    } else {
        NSLog(@"Failed to get search results");
    }
}

更新：我也试过这个，因为它在另一个类似问题的答案中被接受，但它没有奏效：

NSURLConnection *loginConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO];
[loginConnection scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
[loginConnection start];

基于这个问题：Why NSURLConnection delegate methods don't get call, when using the global dispatch queue?

4

3 回答 3

4

我已经开始了一个 SO 帖子，展示了如何使用NSURLConnectionwithdispatch_async和配置NSRunLoop

使用信号量实现的 NSURLConnection 阻塞包装器

您会感兴趣的代码是：

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    [NSURLConnection connectionWithRequest:request delegate:self];

    while(!self.finished) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
    }
});

并在 中connectionDidFinishLoading，设置finished为 YES：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    self.finish = YES;
}
于 2012-12-05T22:27:30.267 回答
4

iphonedevsdk.com 论坛的某个人为我回答了这个问题：

http://www.iphonedevsdk.com/forum/iphone-sdk-development/97415-dispatch_async-nsurlconnection.html

答案是使用：

 [self performSelectorOnMainThread:@selector(getPrices) withObject:Nil waitUntilDone:NO];
于 2012-01-27T14:09:27.590 回答
0

我认为您正在自动释放连接并且没有保留对它的任何引用，因此它会出现内存不足。删除自动释放调用，看看问题是否消失。如果是这样，请在完成连接后找到一种释放连接的方法，以免泄漏。

于 2012-01-20T12:33:02.790 回答