Iphone 使用UIProgressView和ASIHTTPRequest跟踪下载进度

我正在使用ASINetworkQueue下载一系列要在特定视图中显示的图像

Mi问题是，当我打开视图，然后立即关闭它时，在请求完成之前，UIProgressView尝试更新时需要一段时间，然后它崩溃（EXC_BAD_ACCESS），因为它不再存在（视图被取消）。在卸载视图之前，我尝试将委托设置为零，但没有帮助

这是负责创建队列和添加请求的代码部分

- (void)doNetworkOperations
{
    // Stop anything already in the queue before removing it
    [[self networkQueue] cancelAllOperations];

    // Creating a new queue each time we use it means we don't have to worry about clearing delegates or resetting progress tracking
    [self setNetworkQueue:[ASINetworkQueue queue]];
    [[self networkQueue] setDelegate:self];

    // if I have little files to download, use accurate progress
    // if I have lots, it's not worth it.
    if ([promosInfo count]<=4) {
        [[self networkQueue] setShowAccurateProgress:YES];
    }
    [[self networkQueue] setDownloadProgressDelegate:progressControl];
    [[self networkQueue] setRequestDidFinishSelector:@selector(requestFinished:)];
    [[self networkQueue] setRequestDidFailSelector:@selector(requestFailed:)];
    [[self networkQueue] setQueueDidFinishSelector:@selector(queueFinished:)];

    NSInteger i=0;
    for (id row in promosInfo){
        NSURL *url = [NSURL URLWithString: [row objectForKey:@"imgSource"]];
        ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL: url];
        [request setTag:i];
        [[self networkQueue] addOperation:request];
        i++;
        url = nil;
        request = nil;
    }

    [[self networkQueue] go];
}

---

如何让ASINetworkQueue停止跟踪进度？正如我提到的，我尝试将委托设置为nil，但似乎不起作用。

我完成了以下代码并实现了进度条的功能

在类中，我将下载progressBar并将其保存为键的值，在字典中每个请求的url都不同，然后将该字典保存到类名Singleton中

    UIProgressView *_progressBar = [[UIProgressView alloc] init];
    ASIHTTPRequest *request;
    request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:trimmedString]];
    [request setDelegate:self];
    [request setDownloadDestinationPath:filePath];
    [request setDownloadProgressDelegate:_progressBar];
    [request setShowAccurateProgress:YES];
    [request setShouldContinueWhenAppEntersBackground:YES];
    [request setDidFinishSelector:@selector(downloadedSuccessfully:)];
    [request setDidFailSelector:@selector(downloadedFailure:)];
    [[[MySingleton sharedSingleton ]getProgressValue] setValue:_progressBar forKey:trimmedString];

然后在我要显示进度条的视图控制器中，我编写了以下代码：它从Singleton类的dictionary中读取每个单元格进度条的值，并显示在表中。如果完成，它不会显示，因为在dic中，该值将为零，但您必须为此重新加载表

UIProgressView *progressBar = (UIProgressView *)[[[MySingleton sharedSingleton] getProgressValue] valueForKey:[dictionary valueForKey:@"SongUrl"]];
    [progressBar setFrame:CGRectMake(215, 27, 40, 10)];
    [cell.contentView addSubview:progressBar];

---

尝试在viewDidUnload中添加此代码，以查看其是否有效

for (ASIFormDataRequest *req in [networkQueue operations]) {
    [req cancel];
    [req setDelegate:nil];
}

[networkQueue reset];
[networkQueue cancelAllOperations];
[networkQueue setDelegate:nil];

---

我最终通过更改取消请求、将委托设置为nil以及类似的从viewdiload到ViewWillDissapear：（BOOL）Animated实现了这一点。

我真的认为您的解决方案可以做到，但它仍然尝试访问UIProgressView，但访问失败。

for (ASIFormDataRequest *req in [networkQueue operations]) {
    [req cancel];
    [req setDelegate:nil];
}

[networkQueue reset];
[networkQueue cancelAllOperations];
[networkQueue setDelegate:nil];