Question

我正在使用 AFNetworking 库，如何使用AFNetworking Library下载大量数据以显示更好的性能？

我已按照以下步骤操作：

＆＃34;的的.zip ＆＃34;从服务器下载内容的文件。

我添加了一个网址，像这样我有很多网址从服务器下载内容。这需要太多时间。如何从服务器执行快速下载。

我的查询是：如果在服务器上找不到网址，则会执行失败状态。但是＆＃34; .zip＆＃34;存储在文档文件夹中，其中包含零字节等空内容。

在尝试提取 .zip 时，它会显示 .cpgz 格式。让我们知道如何解决这个问题？

-(void)downloadSingFile:(NSUInteger )activityAtIndex totalCount:(NSUInteger )lessonTotalCount{
    // http://118.102.131.158/IYG_wrapper/IYG_updated/IYG_G7_L03/IYG_UN_Mall.zip

    NSString *activityUrl = [filterObjects objectAtIndex:activityAtIndex];
    NSURL *zipFileAtUrl  = [NSURL URLWithString:[activityUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
    BOOL success = [libraryObj createFolderWithName:rootName];
    if (success) {
        activityPath = [[[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:rootName] stringByAppendingPathComponent:[zipFileAtUrl lastPathComponent]];
    }
    NSURLRequest *request = [NSURLRequest requestWithURL:zipFileAtUrl];
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:activityPath append:NO];

    [operation setCompletionBlock:^{
        sleep(1);
        NSLog(@"sucessfully downloaded file %d",activityIndx);
        [self extractSingleActivityAtindex:activityIndx];

    }];
    [operation start];

    [operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
        float percentDone = ((float)(totalBytesRead) / (float)(totalBytesExpectedToRead));
        self.tableView.alpha = 0.7;
        progressView.hidden = NO;
        progressAlert.hidden = NO;
        progressAlert.labelText = @"Downloading..";
        [self updateProgress:percentDone];
        NSLog(@"progress float value is: %.2f",percentDone);
    }];

}

1.请告诉我们，现在我不想下载文件夹路径中存在的内容，也让我们知道该文件是否已经成功下载。

Answer 1

有几点想法：

如果您想知道它是否成功，而不是使用setCompletionBlock，则应使用setCompletionBlockWithSuccess:failure:。
在相关主题中，我可能倾向于将文件下载到某个临时文件（在NSTemporaryDirectory()文件夹中），并且只有在成功下载后，才将其移动到Documents文件夹。您希望完全消除任何正在进行下载的可能性，从而导致文档中的文件。
如果您不想下载Documents文件夹中已存在的文件，则必须自己编写该逻辑（即使用NSFileManager查看文件是否存在，如果不存在，然后才启动下载）。

取消sleep电话。你永远不想sleep（尤其是主线程）。如果您真的想在一秒钟之后触发某些事情，请使用dispatch_after：

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
    NSLog(@"sucessfully downloaded file %d",activityIndx);
    [self extractSingleActivityAtindex:activityIndx];
});

Answer 2

您需要注意以下几点才能实现您的功能

下载前检查文件是否已存在
在activityPath

供参考，请查看以下代码段。

-(void)downloadSingFile:(NSUInteger )activityAtIndex totalCount:(NSUInteger )lessonTotalCount{
// http://118.102.131.158/IYG_wrapper/IYG_updated/IYG_G7_L03/IYG_UN_Mall.zip

NSString *activityUrl = [filterObjects objectAtIndex:activityAtIndex];
NSURL *zipFileAtUrl  = [NSURL URLWithString:[activityUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
BOOL success = [libraryObj createFolderWithName:rootName];
if (success) {
    activityPath = [[[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:rootName] stringByAppendingPathComponent:[zipFileAtUrl lastPathComponent]];
}
 if ([[NSFileManager defaultManager]fileExistsAtPath:activityPath]) {
     NSLog(@"File Already Exist");
     [self extractSingleActivityAtindex:activityIndx];
     return;
 }
NSURLRequest *request = [NSURLRequest requestWithURL:zipFileAtUrl];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.outputStream = [NSOutputStream outputStreamToFileAtPath:activityPath append:NO];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    sleep(1);
    NSLog(@"sucessfully downloaded file %d",activityIndx);
    dispatch_async(dispatch_get_main_queue(), ^() {
       [self extractSingleActivityAtindex:activityIndx];
    });


} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    //    NSLog(@"ERR: %@", [error description]);
    [[NSFileManager defaultManager]removeItemAtPath:activityPath error:nil];

}];

[operation start];

[operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
    float percentDone = ((float)(totalBytesRead) / (float)(totalBytesExpectedToRead));
    self.tableView.alpha = 0.7;
    progressView.hidden = NO;
    progressAlert.hidden = NO;
    progressAlert.labelText = @"Downloading..";
    [self updateProgress:percentDone];
    NSLog(@"progress float value is: %.2f",percentDone);
}];

}

如何使用AFNetworking Library下载大量数据以显示ios中更好的性能？

2 个答案: