6

想要在 iOS 7 中下载文件之前在某个服务器上找到文件的大小...我有一个 NSURLConnectionDelegate 方法，但在 iOS 4.3 之后它已被弃用

这是那个方法：

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
4

7 回答 7

11

使用 HEAD 方法发出请求。例如：

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"HEAD"];

此请求将与 GET 相同，但不会返回正文。然后打电话

long long size = [response expectedContentLength];

NSURLConnection 的完整示例（当然也适用于 NSURLSession）：

NSURL *URL = [NSURL URLWithString:@"http://www.google.com"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
[request setHTTPMethod:@"HEAD"];
NSHTTPURLResponse *response;
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error: nil];
long long size = [response expectedContentLength];
NSLog(@"%lld",size);

这对于基于 Last-Modified 标头有条件地下载也很有用（假设服务器向您发送了该标头）。

if ([response respondsToSelector:@selector(allHeaderFields)]) {
    NSString *lastModifiedString = [[response allHeaderFields] objectForKey:@"Last-Modified"];
}
于 2013-10-11T11:25:25.237 回答
2

您应该改用Note : DATADelegateNSURLConnectionDataDelegate

及其didReceiveResponse:发送HEAD 请求以获取标头的方法：

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response;

然后您可以通过@Port 的建议获得响应大小：

long long size = [response expectedContentLength];
于 2013-10-11T11:30:34.670 回答
1

对于Swift使用这些步骤，

第 1 步：使用NSURLConnectionDataDelegate。

class ViewController: UIViewController,NSURLConnectionDataDelegate {

第 2 步：创建连接请求。

var request:NSMutableURLRequest = NSMutableURLRequest(URL: NSURL(string: "http://www.twitter.com")!)

// Use **HEAD** request to get http header information.

request.HTTPMethod = "HEAD"

第 3 步：创建连接。

var connection:NSURLConnection = NSURLConnection(request: request, delegate: self)!

第 4 步：使用NSURLConnectionDataDelegate的委托方法

func connection(connection: NSURLConnection, didReceiveResponse response: NSURLResponse)
{
    var size = response.expectedContentLength
    println("size : \(size)")
}

这是完整的代码...

import UIKit

class ViewController: UIViewController,NSURLConnectionDataDelegate {

override func viewDidLoad() {
    super.viewDidLoad()


    var request:NSMutableURLRequest = NSMutableURLRequest(URL: NSURL(string: "http://www.twitter.com")!)
    request.HTTPMethod = "HEAD"

    var connection:NSURLConnection = NSURLConnection(request: request, delegate: self)!

}

func connection(connection: NSURLConnection, didReceiveResponse response: NSURLResponse)
{
    var size = response.expectedContentLength
    println("size : \(size)")
}
}
于 2015-01-27T10:44:29.127 回答
1

你可以使用这个方法，NSURLResponse 对象，它被传递给以下委托方法：

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {

}
-(NSURLRequest *)connection:(NSURLConnection *)connection
        willSendRequest:(NSURLRequest *)request
       redirectResponse:(NSURLResponse *)response {
}

试试这样。。

long long size = [response expectedContentLength];
于 2013-10-11T10:33:31.260 回答
0

试试这个会有所帮助。. . . .

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse
                                                                      *)response
{
    NSHTTPURLResponse * pHttpUrlResponse = (NSHTTPURLResponse *) response;

    if ([response respondsToSelector:@selector(allHeaderFields)])
    {
        NSString * fileLength = [NSString stringWithFormat:@"%lld",[pHttpUrlResponse expectedContentLength]];
    }    
}

快乐编码:)

于 2013-10-11T10:42:44.530 回答
0

也使用URlSession你可以得到这样的文件大小，而无需下载实际数据：

func getPdfSize(for url: URL) {
    var request = URLRequest(url: url)
    request.httpMethod = "HEAD"

    URLSession.shared.dataTask(with: request) { [weak self] (_, response, _) in
        if let response = response {
            let size = response.expectedContentLength
            DispatchQueue.main.async {
                self?.fileSizeLabel.text = ByteCountFormatter.string(fromByteCount: size, countStyle: .file)
            }
        }
    }.resume()
}

还请注意，您可以使用本机 iOSByteCountFormatter将字节数格式化为可读字符串。

Swift 5 中的代码

于 2019-04-05T07:29:58.963 回答
-1

尝试这个，

NSDictionary *fileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:URL error:&attributesError];
NSNumber *fileSizeNumber = [fileAttributes objectForKey:NSFileSize];
long long fileSize = [fileSizeNumber longLongValue];

:)

于 2013-10-11T10:52:57.217 回答