如何用url获得文件大小?(复制)

This question already has an answer here:

这个问题已经有了答案:

Get remote file size via HTTP without downloading said file 1 answer
通过HTTP获取远程文件大小，而不需要下载文件1。

In my iPhone application I need to get the file size, but I have only url of it.

在我的iPhone应用程序中，我需要得到文件大小，但我只有它的url。

If I have file path I can get size like this:

如果我有文件路径，我可以得到这样的大小:

NSDictionary* attributeDict = [[NSFileManager defaultManager] attributesOfItemAtPath:resourcePath error:nil];
NSNumber* fileSizeObj = [attributeDict objectForKey:NSFileSize];
long long fileSizeVal = [fileSizeObj longLongValue];

How can I correctly get file size if I have url ?

如果我有url，如何正确地获取文件大小?

1 个解决方案

#1

Use NSURLConnection with Head request, the response will have expectedContentLength:

使用NSURLConnection与Head请求，响应将预期内容长度:

Request

请求

NSMutableURLRequest * req = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://cdn.sstatic.net/*/img/apple-touch-icon.png"]];
[req setHTTPMethod:@"Head"];
NSURLConnection * con = [[NSURLConnection alloc] initWithRequest:req
                                                    delegate:self];
[con start];
[con release];

Delegate

委托

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"didReceiveResponse (%lld)", response.expectedContentLength);
}

Note it might be negative:

注意它可能是消极的:

#define NSURLResponseUnknownLength ((long long)-1)

For NSURLSession, use tasks factory methods that are accepting NSURLRequest objects as parameters, e.g. - (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request completionHandler:(void (^)(NSData *data, NSURLResponse *response, NSError *error))completionHandler:

对于NSURLSession,使用工厂方法任务接受NSURLRequest对象作为参数,例如-(NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)请求completionHandler:(空白(^)(NSData *数据,NSURLResponse *反应,NSError *误差))completionHandler:

#1