Question

我想下载一个具有暂停/恢复功能的文件。我读了苹果文档，我得到了NSUrldownload支持相同，但它不适用于iOS。我正在尝试NSUrlconnection，但没有工作。 我不想使用任何第三方库，我想自己实现它，下面是我尝试的代码片段。

NSString *fileName = [NSString stringWithFormat:@"~%@",[[url componentsSeparatedByString:@"/"] lastObject]];

int dataLength = [[self checkDocDirectoryforFileName:fileName] length];
//dataLength = 0;
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];

[request setValue:@"audio/mpeg" forHTTPHeaderField:@"Content-Type"];
[request setValue:@"bytes" forHTTPHeaderField:@"Accept-Ranges"];
[request setValue:@"Keep-Alive" forHTTPHeaderField:@"Connection"];
[request setValue:[NSString stringWithFormat:@"%d",dataLength] forHTTPHeaderField:@"Content-Length"];
NSLog(@"Request header  %@", [request allHTTPHeaderFields]);
NSURLConnection *conn = [NSURLConnection connectionWithRequest:request delegate:self];