Ios ASIHTTPRequest设置下载目标路径失败

我有一个方法可以查找某个pdf，如果它在本地找不到它，它会使用AsittpRequest异步下载它。但是，当线路出现以下情况时，请求总是失败： [请求设置下载目的路径：currentDetailItem]； 如果未注释，则请求将启动，进度将增加，直到100%，然后执行请求失败块

以下是请求失败时的相关NSLog：

2012-08-16 12:08:34.398 XXXX[1675:707] Request started with url :http://XXXX.com/gwas/sites/default/files/Responding%20to%20Severe%20Weather%20Events.pdf
filePath :/var/mobile/Applications/322C24CF-9664-403D-9CC5-13C396F39F84/Documents/Responding%20to%20Severe%20Weather%20Events.pdf
2012-08-16 12:08:39.018 XXXX[1675:707] Request failed:HTTP/1.1 200 OK

以下是该方法的代码：

- (void)setDetailItem:(NSString *)newDetailItem {
    NSArray *downloadPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSArray *components = [newDetailItem componentsSeparatedByString:@"/"];
    NSString *filePath = [[downloadPaths objectAtIndex:0] stringByAppendingFormat:@"/%@", [components lastObject]];
    currentDetailItem = filePath;

    if (![self fileExistsLocally:[components lastObject]]) {
        //Download the file
        [self displayProgressView];
        ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:newDetailItem]];
        [request setDownloadDestinationPath:currentDetailItem];
        [request setDownloadProgressDelegate:progressBar];
        [request setCompletionBlock:^
         {
             [self showPdf:currentDetailItem];
             [self hideProgressView];
             NSLog(@"%f, Request finished :%@", progressBar.progress, request.responseStatusMessage);
         }];
        [request setFailedBlock:^
         {
             NSLog(@"Request failed:%@", request.responseStatusMessage);
             [self hideProgressView];
             [SVProgressHUD showErrorWithStatus:@"Request failed"];
         }];
        [request startAsynchronous];

        NSLog(@"Request started with url :%@\nfilePath :%@", newDetailItem, currentDetailItem);
    }
    else {
        [self showPdf:currentDetailItem]; 
    }
}

---

如果我注释行[request setDownloadDestinationPath:currentDetailItem]；如果成功，则请求成功。有什么想法吗？谢谢

对于任何感兴趣的人，我通过切换到NSURLConnection解决了这个问题，下面是代码：

- (void)setDetailItem:(NSString *)newDetailItem {
    NSArray *downloadPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSArray *components = [newDetailItem componentsSeparatedByString:@"/"];
    NSString *filePath = [[downloadPaths objectAtIndex:0] stringByAppendingFormat:@"/%@", [components lastObject]];
    currentDetailItem = filePath;

    if (![self fileExistsLocally:[components lastObject]]) {
        [self displayProgressView];
        data_ = [[NSMutableData alloc] init];
        NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:newDetailItem] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
        NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self startImmediately:YES];
        if (!connection) {
            [SVProgressHUD showErrorWithStatus:@"Request failed"];
            return;
        }
        else {
            data_ = [[NSMutableData alloc] init];
        }
    }
    else {
        [self showPdf:currentDetailItem]; 
    }
}

#pragma mark NSURLConnectionDelegate methods

- (void)connection: (NSURLConnection*) connection didReceiveResponse: (NSHTTPURLResponse*) response
{
    if ([response statusCode] == 200) {
        currentDownloadSize = [response expectedContentLength];
    }
    [data_ setLength:0];
}

- (void) connection: (NSURLConnection*) connection didReceiveData: (NSData*) data
{
    [data_ appendData:data];
    progressBar.progress = ((float) [data_ length] / (float) currentDownloadSize);

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    //Save file locally
    NSURL *url = [NSURL fileURLWithPath:currentDetailItem];
    NSError *error = nil;
    [data_ writeToURL:url options:0 error:&error];
    if (error) {
        NSLog(@"Write failed with error:%@", error);
    }
    else {
        NSLog(@"Request successful");
        [self showPdf:currentDetailItem];
    }

    [self hideProgressView];
}

- (void)connection:(NSURLConnection *)connection
  didFailWithError:(NSError *)error
{
    [self hideProgressView];
    [SVProgressHUD showErrorWithStatus:@"Request failed"];
    NSLog(@"Connection failed! Error - %@ %@",
          [error localizedDescription],
          [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
}

---

假设您可以单步执行并查看/why/asi正在调用failure方法。