暂停/恢复Objective-C中的下载 [英] Pause/Resume downloads in Objective-C

问题描述

好的。希望这将是我最后一个关于我正在Objective-C写的下载管理员的帖子。除了暂停/恢复功能外，一切似乎都很好。我的问题是，当下载尝试从它所在的地方继续下去时，它会将其接收到的数据附加到该文件，但仍然似乎正在尝试下载整个文件。这会导致一个大于原始文件的文件。这是我用来下载文件的代码。我做错了什么？

Alright. Hopefully this will be my last post about the download manager I am writing in Objective-C. Everything seems to work well except the pause/resume functionality. My issue is that when a download tries to continue from where it left off, it appends the data it receives to the file, but it still seems that it's trying to download the entire file. This results in a file that is larger than the original file is supposed to be. Here is the code I am using for downloading files. Am I doing something wrong?

-(void)start:(unsigned int)fromByte {
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:self.url] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:DEFAULT_TIMEOUT];

    // Define the bytes we wish to download.
    NSString *range = [NSString stringWithFormat:@"bytes=%i-", fromByte];
    [request setValue:range forHTTPHeaderField:@"Range"];

    // Data should immediately start downloading after the connection is created.
    self.urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:TRUE];

    if (!self.urlConnection) {
        #warning Handle error.
    }
}

推荐答案

终于弄清楚了。事实证明，我从文件的属性中获取了'getFilesizeInBytes'方法，但是我已经从文件的属性获取了 NSFileSize 直接将其转换为 int 。这造成的数量比现在应该是大约20倍。我可以使用 [@intValue] 来解决这个问题。一旦这被修复，服务器能够给出我的文件的其余部分，从正确的字节开始。似乎在我的问题不在于服务器不符合我的请求，但是由于我要求数据远远超出我的要求，所以它不能文件的最后一个字节。

I finally figured this out. It turns out that the 'getFilesizeInBytes' method I had was get the NSFileSize object from the file's attributes, but I was directly casting this to an int. This caused the number to be about 20 times larger than it should have been. I was able to fix this by using [@"" intValue]. Once this was fixed, the servers were able to give me the rest of the file starting with the correct byte. It seems that before my issue was not that the server wasn't honoring my request, but that it couldn't honor my request due to me requesting data that was well beyond the final byte of the file.

这篇关于暂停/恢复Objective-C中的下载的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！