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目前我正在实施文件下载应用程序。 在我的应用程序服务器中有大约2500个资源文件，我需要将这些文件从服务器下载到我的文档目录。遇到多个文件下载问题
我的代码：
@implementation DownloadManager
{
NSURLSession *session;
BOOL downloading;
}
#pragma mark - NSURLSessionDownloadDelegate
// Handle download completion from the task
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location
{
NSInteger index = [self assetDownloadIndexForDownloadTask:downloadTask];
if (index < 0)
{
return;
}
DownloadHelper *movieDownload = _assetsToDownload[index];
// Copy temporary file
NSError * error;
[[NSFileManager defaultManager] copyItemAtURL:location toURL:[NSURL fileURLWithPath:[movieDownload localPath]] error:&error];
downloading = NO;
}
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didResumeAtOffset:(int64_t)fileOffset expectedTotalBytes:(int64_t)expectedTotalBytes
{
// Required delegate method
}
// Handle task completion
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
{
if (error)
NSLog(@"Task %@ failed: %@", task, error);
NSLog(@"Task %@ Success: %@", task, error);
if ([_assetsToDownload count])
{
[_assetsToDownload removeObjectAtIndex:0];
}
downloading = NO;
if ([_assetsToDownload count])
{
[self downloadFiles];
}
else
{
[self downloadAssets];
}
}
// Handle progress update from the task
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
NSInteger index = [self assetDownloadIndexForDownloadTask:downloadTask];
if (index < 0) return;
// DownloadHelper *movieDownload = _assetsToDownload[index];
double progress = (double) (totalBytesWritten/1024)/(double) (totalBytesExpectedToWrite/1024);
dispatch_async(dispatch_get_main_queue(), ^{
// Showing progress
});
}
#pragma mark - Movie Download Handling & UI
// Helper method to get the index of a Asset from the array based on downloadTask.
- (NSInteger)assetDownloadIndexForDownloadTask:(NSURLSessionDownloadTask *)downloadTask
{
NSInteger foundIndex = -1;
NSInteger index = 0;
for (DownloadHelper *asset in _assetsToDownload)
{
if (asset.downloadTask == downloadTask)
{
foundIndex = index;
break;
}
index++;
}
return foundIndex;
}
- (void)addAssetDownload
{
DownloadInfo *info = nil;
NSString *assetFolder = nil;
for (int index = 0; index<[_assets count]; index++)
{
info = [_assets objectAtIndex:index];
NSURL *url = [NSURL URLWithString:info.assetURL];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithRequest:request];
DownloadHelper *assetDownload = [[DownloadHelper alloc] initWithURL:url downloadTask:downloadTask];
assetDownload.assetName = info.assetName;
if (info.categoryId == 1)
{
assetFolder = [self getImagePath:info.assetName];
}
else if (info.categoryId == 2)
{
assetFolder = [self getVideoPath:info.assetName];
}
else if (info.categoryId == 3)
{
//assetFolder = [self getDBPath:info.assetName];
}
else
{
assetFolder = [self filePath:info.assetName];
}
assetDownload.assetFolder = assetFolder;
[_assetsToDownload addObject:assetDownload];
}
}
// Initialize the download, session and tasks
- (void)initialize
{
for (DTEDownloadHelper *movieDownload in _assetsToDownload)
{
// Cancel each task
NSURLSessionDownloadTask *downloadTask = movieDownload.downloadTask;
[downloadTask cancel];
}
// Cancel all tasks and invalidate the session (also releasing the delegate)
[session invalidateAndCancel];
session = nil;
_assetsToDownload = [[NSMutableArray alloc] init];
// Create a session configuration passing in the session ID
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfiguration:@"DTEDownloadBackground"];
sessionConfiguration.discretionary = YES;
session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];
[self addAssetDownload];
// Reset the UI
downloading = NO;
[self downloadFiles];
}
// Download handler
- (void)downloadFiles
{
if ([_assetsToDownload count] > 0)
{
// Acquire the appropriate downloadTask and respond appropriately to the user's selection
NSURLSessionDownloadTask * downloadTask = [_assetsToDownload[0] downloadTask];
if (downloadTask.state == NSURLSessionTaskStateCompleted)
{
// Download is complete. Play movie.
// NSURL *movieURL = [NSURL fileURLWithPath:[_assetsToDownload[0] localPath]];
}
else if (downloadTask.state == NSURLSessionTaskStateSuspended)
{
// If suspended and not already downloading, resume transfer.
if (!downloading)
{
[self showHUD:[NSString stringWithFormat:@"Downloading %@",[_assetsToDownload[0] assetName]]];
[downloadTask resume];
downloading = YES;
}
}
else if (downloadTask.state == NSURLSessionTaskStateRunning)
{
// If already downloading, pause the transfer.
[downloadTask suspend];
downloading = NO;
}
}
}
- (void)downloadAssets
{
_assets = [self retreiveAssets]; // Getting the resource details from the database
if (![_assets count])
{
// Hide progress
}
[self addAssetDownload];
[self downloadFiles];
}
@end
问题：
有时它下载的第一个文件，并停在那里，下次启动时起，它没有下载任何东西。直到现在我还找不到这个问题，因为这个问题我几乎浪费了一天的时间。请帮我找到问题。提前致谢。
@Rob：感谢您的信息，我会检查它 –