Question

想要在iOS 7中下载文件之前在某个服务器上查找文件的大小...我有一个NSURLConnectionDelegate方法，但在iOS 4.3之后不推荐使用

这是方法：

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

Answer 1

使用HEAD方法发出请求。例如：

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

此请求与GET相同，但不会返回正文。然后拨打

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标头进行有条件下载也很有用（假设服务器发送给您）。

if ([response respondsToSelector:@selector(allHeaderFields)]) {
    NSString *lastModifiedString = [[response allHeaderFields] objectForKey:@"Last-Modified"];
}

Answer 2

您应该使用NSURLConnectionDataDelegate 注意：DATADelegate

及其didReceiveResponse:方法发送HEAD request以获取标题：

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

然后你可以通过@Port的建议获得响应大小：

long long size = [response expectedContentLength];

Answer 3

你可以使用这个方法，NSURLResponse对象传递给下面的委托方法：

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

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

试试这个..

long long size = [response expectedContentLength];

Answer 4

对于 Swift ，请使用以下步骤

第1步：使用 NSURLConnectionDataDelegate 。

class ViewController: UIViewController,NSURLConnectionDataDelegate {

第2步：为连接创建请求。

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)")
}
}

Answer 5

试试这会有所帮助。。。。。

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

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

快乐的编码：）

Answer 6

也可以使用data class Responseval(val `data`: List<Data>, val message: String, val success: Boolean) data class Data(val created_at: String, val id: Int, val name: String, val status: Int, val updated_at: String)来获得这样的文件大小，而无需下载实际数据：

URlSession

请注意，您还可以使用本机iOS 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() }将字节数格式化为可读的字符串。

Swift 5中的代码

Answer 7

试试这个，

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

：）

如何在iOS 7中下载之前查找文件的大小？

7 个答案: